A UV filter actually does very little "protecting" and the UV filtration isn't necessary with digital imaging, the way it was with film.

If you think a thin piece of glass is somehow going to "save" your lens... watch this: https://www.youtube.com/watch?v=P0CLPTd6Bds

Obvious in that video (where someone actually tests the efficacy and usefulness of "protection" filters), lenses are "tougher" than most people think and a "protection" filter is largely a waste of money (and "protection" was not the reason we used UV, sky, and 81A, 81B warming filters frequently with film... we used them because most color film was overly sensitive to UV light, causing a bluish tint in images).

Use the correct lens hood and the cap that came with the lens. Either of those will do a much better job of protection than a thin piece of glass ever could! In fact, when using a filter, you should be even more faithful about using the hood and cap... to protect the filter!

A UV filter actually does very little "protecting" and the UV filtration isn't necessary with digital imaging, the way it was with film.

If you think a thin piece of glass is somehow going to "save" your lens... watch this: https://www.youtube.com/watch?v=P0CLPTd6Bds

Obvious in that video (where someone actually tests the efficacy and usefulness of "protection" filters), lenses are "tougher" than most people think and a "protection" filter is largely a waste of money (and "protection" was not the reason we used UV, sky, and 81A, 81B warming filters frequently with film... we used them because most color film was overly sensitive to UV light, causing a bluish tint in images).

Use the correct lens hood and the cap that came with the lens. Either of those will do a much better job of protection than a thin piece of glass ever could! In fact, when using a filter, you should be even more faithful about using the hood and cap... to protect the filter!

A quality Circular Polarizer is a much more useful filter enhancing images and far better use of your money (though a C-Pol also should not be left on a lens most of the time, only installed when actually needed and serving a purpose... a C-Pol can "cost" as much as 2 stops of light, which may force you to unnecessarily use too high an ISO or too slow a shutter speed).

At B&H Photo and Adorama (and maybe elsewhere)... B+W "Kaesemann" C-Pol are among the least expensive of the highest quality C-Pol.

Fore example, in 77mm size the B+W "F-Pro" (Schott glass, sealed edges, finer foils, high transmissive, 8-layer MRC multi-coated, brass frame) is about $80

And the slimmer B+W "XS-Pro" (same as above, but slimmer frame and 16-layer "Nano MRC" multi-coated) 77mm is just over $100. The most comparable other brand (Heliopan... nearly identical specs) cost more than 2X as much. Heck, even Hoya of similar quality are at least 50% more expensive.

All the above said, yes I have UV filters to fit my lenses. They were pretty low priority for me and I only rarely use them, but I added them to my kit a little at a time "just in case". I store them separately in my bag until actually needed, on odd occasions when they might actually serve a purpose... such as when out shooting in a sand storm or when shooting at the beach with a lot of salt spray in the air (I'd rather clean that off a filter than off a lens). As a result, probably 98% of the time or more the UV filters remain in my camera bag and I'm either using my lenses with other, actually useful filters or without any filter at all most of the time... But almost always with hood while shooting and capped when stored. Some lenses in my "daily user" kit are 15+ years old ... while some vintage lenses I use are many decades old. None of them show any issues due to lack of "protection" while making tens or hundreds of thousands of images.

If you still want a UV and have money to burn on a rarely needed filter, once again the B+W are a great value for their quality. The last time I looked, the standard "010" MRC (Schott glass, 8-layer MC, brass frame) in 77mm is $40 and "010" XS-Pro (slim, 16-layer "Nano" MC) 77mm is about $5 more. (Note: B+W also makes less expensive "SC" or single coated filters. I don't use those.)

BTW, the Lenstips comparisons and prices that were linked in an earlier response above are horribly out of date (were done in 2009).

And, yes, a "cheap" filter can be a nightmare. When I hire second shooters who will be using their own gear, I ask them to remove any filters. I can recall one who didn't listen and put me in a position where I had to correct green flare issues in nearly all 1200 images he took! That was many hours of extra work for no good reason. Cheap filters also can effect resolution and sharpness... can even interfere with focus accuracy and increase chromatic aberrations. High quality, multi-coated filters are a better bet, but even they can have some negative effects in challenging lighting conditions. Some people say, "Well, I'll just remove the filter in those situations." Yeah, right! I bet! Personally I would have no time to stop shooting and remove a filter... if I remembered to do so. To me it makes far more sense to do it the other way around... .shoot filterless and add a filter when actually needed.