mmm.... around 10 trialsters i think. its hard to progres. people dont know what is trials. and the ones who do know, think it's too demanding for them to even try.
there are more xc, fr, trails and even bmx riders then trials riders.
also, a trials specific bike (to build from scratch) is not as cheep as the same urban/street machine of the same level, because of the expensive frame and parts (even the more cheep parts are more expensive then a complite mid leveled bike). riders want a bike that can handle anything and with a seat (Y) .