i have a head unit in my old merc estate, i believe it came from one of the discount supermarkets over here (unbranded) and while it doesn't have the search facilities - at least, i don't think it has - it takes sd cards and a usb. i always have a 2gb sd in there, the usb will vary, sometimes a laptop hard drive (it struggles with 25gig of data) or a 2gig usb stick with y current fave stuff on it.

guess it cost the equivelent of about $75 at the current rates. cheap as chips!