I would say a good, cheap distortion pedal would be the Cool Cat distortion from Danelectro. I bought one from my guitar teacher for jazz band to add a small amount to stand (like a transparent overdrive). I've used that on my bass and guitar and it is a godsend. I've used it for everything, even to get a Rickenbacker 4001 tone on an ibanez soundgear. I recommend it solely. The true bypass feature is great if you're worried about your tone. Check out the other cool cats too if you want other nice yet affordable pedals.