You're very welcome. Let us know how it goes. My issues with Costco (or any mass-printing place) was submitting images that were too dark and too saturated. I had to learn to adjust from optimal look on computer monitor to the printing process.

You can get the printer profile info from Costco and set up properly, but that kind of attention to detail was beyond my interest

FYI, there is a dedicated printer forum on UHH also:
https://www.uglyhedgehog.com/s-120-1.html

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taj334: I have the same vintage (late 2012) MBP and thought I'd drop a note to let you (and others) know I recently installed PSE 2019 on it- (operating under Mojave, current), and I am experiencing no problems. There might well indeed be Mojave incompatibilities with PSE 15- I don't know, but I just wanted to let you know you needn't be scared-off of *newer* version of PSE (2019) AND running Mojave on your year/model MBP. It would be a shame to have PSE15 dictate/relegate you to High Sierra. (I'm also going to propose that your Apple "technician" took an easy road, and that your problem could have been solved without pushing you back to High Sierra- but then you get into the "well call adobe" syndrome- good luck with that one :>)
Our MBPs are the very oldest that can run Mojave; I have had no problems whatsoever. Happy shooting.

I really think you will appreciate the large screen and comfort of using an I-Mac desktop. I bought a refurbished one from Apple and it came with 8 gigs of memory and that was five, trouble free and productive years ago. I use it for all my photo work, plus academic work for the classes I teach. It is great! I back it up with a Seagate external hard drive with a 3 terabyte capacity. It is a fine setup and I recommend you taking a look at getting a refurbished one from Apple. Mine cost me right at a thousand and came with a CD reader.

What does, "bit the dust mean"? As extreme as the hard drive won't spin, or something more like the operating system won't execute?
With either one a new hard drive is less than $100.
It it's the latter you can get the new hard drive and reload the operating system and you're good to go. Then you can get a case for the old drive that will let you hook it up as a secondary drive and download all you're photos and stuff off it. They're less than $20. Moving the programs is a bit more hassle and requires some technical expertise but it can be done.

You have a lot of options, if you want to stick with a MacBook Pro.

One option is replacing the hard drive in your existing computer with a greater capacity hard drive or an SSD. If you are the least bit handy with tools, and you have fine motor skills (dexterity), well-corrected close vision, and patience, AND can follow instructions to the letter, this would be the approach I would take. At least, you should consider exploring it.

Other World Computing, AKA OWC or http://www.macsales.com, has all sorts of options you might choose. They also have SUPERB, free installation instruction videos, and kits with all the tools and parts you might need to crack the case and swap components. Another great source is http://www.ifixit.com.

Depending upon the exact make and model of your Mac, your options may be quite attractive. I recently upgraded my iMac with double the RAM and an SSD with twice the storage space. This was a job Apple says can't be done by users, but OWC's instructions and parts kits made it possible. It was slow going, and a bit tricky, but TOTALLY worth it.

If you take this route, you can restore your last backup of the old drive to the new one. The path I would take is to format the new drive and install a virgin system 10.14.3 on it. OWC has instructions for that. Once you have the new system (or a new computer), you can use the Migration Assistant Utility in Mac OS to move your old User Profile (and all your data) from the backup to the new drive or Mac. In my case, building a new system with all virgin software installations took about a day and a half. But now, my computer SCREAMS. The extra RAM and the SSD make a tremendous difference.

OWC and many other Internet retailers sell used Macs. These are usually tested, reconditioned, and may be upgraded to your specifications. I bought two 2012 MacBook Pros from OWC for my twins a few years ago, and they still work flawlessly, despite rough handling by college students.

New MacBook Pros are expensive, but if you want to keep a machine for 5-7 years, may be your best choice. You probably don't need the high end, loaded models, but bear in mind that the LATEST MacBook Pros are either not upgradable at all, or only partially upgradable, so you want to get all the SSD drive space and RAM you can afford, right up front. The 13" models are more limited than the 15" models, but the 15" models are much more expensive.