If it says bass, its gotta be more expensive. I have no idea why, but thats just how it works. I think its becuase it has to be bigger for bass, but who knows....
Does he want an auto wah or the traditional wah with the expression pedal/manual wah?
Personally as a bass player myself I bought a used Bass Crybaby wah but did not really care for it. I was able to exchange it for a Boss Auto Wah wich I like better...I also found it difficult to focus on locking in with the drums while messing around with the Cry Baby wah pedal. If your attack is not fairly consistant it just blurs the rhythm section to me.
Now Boss has the AW-3 that has seperate outputs for bass guitar and guitar wich has gotten good reviews ans should be fairly versitle with two optimization options.
I would like to get it now but have been focussing limited resources on upgrading recording equipment.
For more $$ ther is the Mutron III Envelope filter that has several wah like setting and has benn VERY popular with funk bass players but I believe they sell new for $270 -$300.
I was looking for a multi-effect. and i found a bunch of really cheap stuff. go to http://www.wwbw.com and look around under guitar, anything you can think of dirt cheap. have fun