I haveYeah they grow to just over six inches.Having said that they should be looking nice at 4inches.
You don't see many wild livebearers in the shops over here in the UK.Just the normal line bred multi coloured crap.
As you said,best to get them from a trust worthy source so you know you have the real deal.
never seen any kind of wild-type livebearer at an lfs. Would love to stumble across some...especially some Montezumae swords but until then, there's aquabid.