At the much lower end (below BlackMagic), a Canon 5D mark III equipped with Magic Lantern (by thudson of ThunderStrike / ThunderStrike 2 fame) is an exceptional 35mm platform for cash-poor movie makers.

See [0] under "Why not just buy a video camera?", although IIRC the $25K price for the RED is circa 2009, and it's much cheaper now.

[0] http://magiclantern.wikia.com/wiki/Magic_Lantern_Firmware_Wi...