So this has turned out to be a much more difficult question to find an answer to than I ever expected...

I need to run speaker cable from my indoor receiver to wall-mounted
outdoor speakers beside my deck. I was hoping to simply go to the big
box store and have them pull some in-wall CL2/CL3 *AND* UV-resistant
cable for me by the foot.

Not so simple I guess. Although this is clearly done on thousands, or
millions, of homes, I have yet to figure out what type of cable is
proper to use. Landscape cable? (Probably not in-wall rated.) In-wall
cable? (Probably not UV-resistant.) What does everyone use?

The cable used by the previous owners was so damaged by the elements
the corrosion must have gone 5 feet into the wall. So I definitely want
something that will hold up to the weather, but is proper for in-wall
use. I already have a few siding boards off the house for a different
project and thought this would be the perfect chance to patch in my
speaker cable, and never thought it would be so hard to figure out.

I also only need about 25', so the 500ft rolls for $100+ are not what I was looking for...

Also, I'm in Colorado for what that's worth regarding code, etc.

Thanks.