How you want your bass served? The more the merrier so everything drowns in it or there's also some concern about bass quality like texture, extension, etc? What about other aspects of sound like highs, mids, soudstage, overall balance? What music type you listen to?
But anyways here are few well regarded bassy phones under $100 USD all of which I owned or sampled - Klipsch s4, Monster Turbine, Panasonic HJE-900. Latter in my opinion is a gem, albeit a rough one. I'm still debating whether to keep it or Monster Turbine Gold which is twice the price.