elec drums never sub in for real ones... but they can be better(in some ways ie access to djembe sounds!). I'm a guitarist, but drummers everywhere tell me I'm wrong on this: I dare ya...
get a roland vdrum brain. It's hands down the best sounding brain out htere. I have all the sounds from the yamaha dtxpress, all the sounds from the alesis dm5, all the sounds from the vdrum, all the sounds from the ddrum. The roland is the best.
I'd get a roland vdrum (dual or triple trigger) for the snare. I wouldn't spen d the money on the vdrum toms, bd, and cymbals, unless youv'e got it. Oh, yeah, there's a vdrum knock off too. They make great stuff. I'd go with some cheaper pads for toms and cymbols cause the diff is negligable.
If you really wan't to do it down lo... get some piezo triggers from radio shack... buy a practice pad kit(150), and wire up the triggers to 1/4 jacks and place them under the practice pads. This coupled with a dm5, and some cymbal stands... your talking under $400. For cymbals use black frisbees.
Just some thoughts from a non-drummer. Take them for what there worth.