I think $250 is a great fee (rates for Louisville Pipe Band soloists start at $150 for local gigs and go up from there).

The carpet and furniture (and the tree) may absorb some of the sound, but it would still be uncomfortably loud being in the same room with a set of Great Highland pipes (unless the room is the size of a small gym). Even then, no one will want to be standing closer than about 10' for long. There's a reason I wear earplugs when I practice indoors (and my largest room is a little over 10' x 20', with an 8' ceiling). I still recommend trying to find a piper with something quieter.

A smaller room for tuning/storage is a great plus, but often we pipers have to make do with what's offered.