ok so me and my friends are starting a band im going to play bass guitar which i already have but the thing is i dont have a bass amp. My band will be playing very heavy punk such as grunge and are going to jump straight into nirvana covers our guitarist has a valveking 112 50w amp with a ds-2 pedal. I just need suggestions on what kind of amp i should get that can keep up with a 50w tube amp and a very agressive drummer.

P.S im on a budget looking for anything around 200-400$ and when you suggest an amp will you give me a reason for your suggestion and any other feedback on what to advoid.