mmm your endler/guppy cross could be easily obtained through "feeder" guppies. bout 33cents here. they have gone up since i have been small. i actually have one like that except it contains more blue. yet since ive added into the saltwater tank the dual tail has disappeared. most people would fall back on this and just say its a non-endler since most guppies are a hybrid anyways. knowing that it will always have a trace of endler's
note: feeder guppies are guppies in which do not have desirable traits in which the person is seeking.