Unfortunately, cheap and modular are rarely in the same sentance. Yes, the Corsairs are awesome PSU's, but they're not cheap. With a CM690, which i have.. (with a 9800GTX+ in it)...you can run most of the wires behind the mobo-tray, and out of sight.. as the PSU is bottom mounted.
The HX series(Corsair-modular), have jumped in price since the summer, but the non-modular models(VX550<-mine,TX650/750) are still decently-priced and are great PSUs as well. GL
