advice on a new amp

I play in a band, and we practice at the guitarist's house (where all the equipment is.) I keep my crappy Fender 15watt bass amp at his house, so I won't have to lug it around all the time. This amp came in a starter pack, so it was fine when i first got it, and now the sound sucks and it buzzes like crazy. Lately, it's been extra annoying, and I know it's time to replace it. I have a good quality Crate 15watt at my house, but I don't want to keep my good amp at his house. I guess the best decision would be to get a new amp for his house. It doesn't have to be top of the line, it just has to get a good sound for a low price. I don't want to have to pay for this amp because it's not even going to stay at my house. In fact, I just bought another bass to stay at his house, and I really don't want to pay for another thing that he is going to be keeping. He also suggested bringing over my 50watt Peavey guitar amp to keep at his house, which isn't that bad of an idea to me because I don't really use it. But if I use it for bass on a regular basis, will it blow out? Will I have to keep it down?

So do you have any advice about a good amp for this situation, using the guitar amp, or how to handle the purchasing with him?