Depending upon the quality you need, as determined by what you want to do with the images, there are different ways you can scan your slides yourself or have them done.
A cheap dedicated film scanner (around $100 US or less) or widely available and inexpensive commercial, low resolution scanning (1-hour film processor quality) might make good enough scans for 4x6 and 5x7 prints, at most.
A quality flatbed scanner is more generally versatile and some of the better ones such as Epson V600 or Canon 9000F are capable of making high enough resolution scans for 6x9, 8x10 or maybe even 11x14 prints. Figure about $200 to $500 US for one of the higher quality that are best able to scan slides (or negs). Other advantages to a flatbed include that you can do batch scans of a sort, a number of images all in one (later separating them with post-processing). Also a flatbed can be used to scan prints other other sheet goods if needed.
Depending upon the quality of the macro lens used and the DSLR it's on, a slide copier rig can be roughly equal to a high-end flatbed scanner at about the best. This also is largely a one-at-a-time process, though each capture can be pretty darned quick.
Better quality is done with a high-end dedicated film scanner.... such as a 5400 pixel per inch Minolta or 4000 ppi Nikon (or more current Plustek, Pacific Image, . These can easily make an 11x14 and possibly bit larger print from a good quality slide or neg. Figure on spending around $500-1000 US to buy one of these scanners (or equivalent, both the Nikon and Minolta are no longer made, but there are other manufacturers making similar now: Plustek, Pacific Imaging and a few others). One problem, these are only for film and with slides many of them can only handle one at a time (with negs many can handle a film strip where 5 images will be scanned in sequence, or perhaps even an uncut roll of up to 36 images). This takes longer, too, at the highest quality levels. One I use takes 10 or 15 minutes per scan at it's highest setting (producing a 130MB 16 bit TIFF file). There are some services offering this level of scanning, but they're a lot more expensive than what you pay at the local 1-hour film processor, so might be something you'd reserve for your better slides.
There are a few high-end dedicated film scanners that can work with batches of mounted slides... that have some form of feeder to automatically process a number of slides. I use an accessory feeder with my Nikon 4000, that can handle up to 40 slides at a time (I set it up and let it run overnight, since each individual scan is still a time-consuming process... I also have to be sure there's plenty of disk space, since every 8 or 9 scans fill up a gigabyte worth of HD storage). This adapter cost over $400 US when new (no longer in production, so can only be bought used now). Some other high-end, dedicated film scanners (Braun and Pacific Images, for example) have means of handling up to 50 mounted slides, but may not be able to handle unmounted slide or neg strips and cost around $1000-1800 US.
I'm sort of assuming your slides are 35mm film... But be aware there are also dedicated film scanners that can handle medium format film in various formats, if needed. (Note: Thanks to their much larger image sizes, medium and large format film also makes for a lot more successful flatbed scanning or copying somehow with a DSLR and macro lens.)
High-end flatbed and dedicated film scanners use a specialty software such as Silverfast Ai, which may or may not be included. If not included it can add $250 US or more to the cost of setting up to do the scans. The best software not only automates the scanning process, but also gives good positive previews of color negatives (removing the orange mask that's common with those), has built-in capability to correct for color shifts that might have occurred with some types of slide film (i.e. Kodachrome, for one), reduces the appearance of film grain, remove scratches and dust automatically, and more.
The very best digital slide conversions are done with drum scanners. Those can do as much as 9000 or 10,000 ppi scans and produce quite large 16 bit TIFF files. You need to have a pretty powerful computer system with a lot of storage space to work with these. The price of purchasing a drum scanner is out of reach of most consumers (the entry-level 6200 ppi Hasselblad costs $13,000 US), but there are services that do this quality of scan for around $20-25 US per image. So you might reserve this level of work for your very best images, that you want to be able to print 16x20 or possibly even larger (I've seen as big as 30x45" prints done from 35mm negs and slides, utilizing medium format internegatives).
So, how big do you want to be able to display your images? How much time do you want to devote to doing the project yourself?
One thing to consider... If you buy a high-end dedicated film scanner, you might consider a used one. My Nikon 4000 cost around $1700 new around 2001, but they now sometimes sell used for under $300 (just check the condition, they do occasionally need cleaning and adjustment... and compatibility with computer since it uses Firewire 400 connectivity... figure on around $100 US for basic Vuescan or $250 for more advanced Silverfast Ai software, too, in order to use it with today's computers... the original software and Twain driver provided with the 4000 ED scanner are not compatible with operating systems after Windows XT).
Then, once you've scanned and saved all your slide images, completed your project, you'd probably be able to turn around and sell off that scanner to recoup some or even much of what you spent initially (after all, this is where a lot of those used scanners come from). You may not be able to resell licensed software, though. Or you might want to keep the scanner if you're still shooting some film occasionally and need to be able to do more scans in the future. The cheapie film scanners tend to be pretty much worthless at resale... while the better, higher-end ones tend to hold their value pretty well.
More info about film scanning can be found on the B&H Photo website (among other places):
https://www.bhphotovideo.com/explora/photography/buying-guide/film-scannersOh, and whatever you do, don't throw away your slides! Store them away carefully after they've been scanned. They are still a more reliable archive, than the scan files stored on hard drives or other digital media.