Using guitar for a bass

Use one of the free bass VSTi in Kontakt Player's free Factory Selection if you can't afford one. For being free, it's quite good with BOD/POD Farm/whatever on it and will be 100x better than using a pitch shifted guitar.
 
Yeah, my bullshit detector didn't go off on Trev either, chill the eff out dude he makes good points.

If you really think that a guitar pitched down is going to sound as good as a real, properly processed bass guitar then just Alt +F4 your DAW. Of course it could sound "good", but the time invested and the tone produced can't compare to equal amounts of time invested in a real bass recording.