UV Filters are rather pricy to purchase and operate. I'm trying to avoid
having to buy one as well.

Purchase price can be steep. Operating isn't bad. I've found you essentially
_never_ need to change the bulb until it no longer lights up. These yearly
bulb change recommendations are (I think) for UV used for drinking water.
In a pond even a weak UV kills some of the microorganisms passing through it
and the ones that aren't can be zapped the next time through. I had my first
UV bulb almost ten years, I repaired it several times by soldering connecting
wires back on or replacing the ballast. It finally corroded away too much to
repair.

I'm sure it was still working because I could notice if it went out by the
water slowly getting murky. I'd check the UV and sure enough, left the switch
off or something.

I believe it helps control parasites and disease as well.

There are some build it yourself plans for them on the web somewhere if you
want to save a little $$.

Hope this helps
Andrew