i'll be honest and say i have no idea what a rich, warm sound is, so take my option with a pinch of salt (and hopefully someone will clarify if they have the sound your after), but it might be worth a look at the Vsonic VSD3S, currently selling for £30 ish.
as i said no idea if they fit the sound you want, but i'm more than happy with the quality of the sound it produces, and use them over my sound magic e10's.