crunch fat boys are a step down quality wise from a rockford he sub...all the above mentioned are kick butt subs but ya'll forgot one from jl..w3 now it might not be the w7 but it fairs quite well with the other subs you mentioned.......idmaxes are smooth too
Unless you get a sub from Ebay I think the best bang for your buck is gonna be the Shiva..Small sealed enclosure and it still hits hard..Another sub I have come to love is the Infinity Perfect 12.1 It is good with SQ and gets plenty loud...It was mentioned b4 but you need to listen to them yourself your ears may have a different preference than mine or whomever.