Here's a shock...

Why not buy a bass guitar?

If you want pure deep and funky bass - learn to play.

(admittedly it wont give you a synth type sound unless you get a decent FX pedal..)

But boy oh boy those grooves are harsh and tough and deep n funky.
Uhmm.. good idea.. But I think we can spent less cash and have a good rentability with the last fruity loops version that has a vst included with emulations of any kind of guitar..
what makes the sound deep its the style of emulation we choose!
The funky part we need to know how to create a funky melody...
Bryan Cox and Angel Alanis are a good example of funky melody producers.. I think the musical notes we can base on its RE ,BIGGER RE, LA, bigger LA , MI , bigger MI!
I just think , I don't have sure.. But we can try to use them to know if it is true about funky sounds.