Hey guys, out riding the past 2 days and it was awesome!

I just found out I have a small leak on my valve stem in the rear tire. I was wondering, when shops fix it, do they have to take the rear wheel off?

I'm asking cuz I notice my rear sprocket looks like its about to wear out and needs replacing soon.

Any1 know how much I can expect for shops to charge for the valve stem fix and sprocket and chain job or any sites I can get a good inexpensive set?

Thanks.