Long time no speak

I've been considering lately the purchase of a Tri oval TRS Yoshi slipon set for my zed. The price seems reasonable and I have to admit I have a soft spot for the yoshi tri ovals.
I'm not overly fussed about a full system but my only question is, is it worth getting the power commander (It would seem the PC V is the only available model for my bike) as well. Or really since they're just slip ons not going to make too much of a difference power commander or not?
This transaction might not actually occur but was looking for thoughts around the use of a PC V + slip ons vs just the use of slip ons for a bit of extra noise

Also, where do people get there bits from in the states, ebay it or is there some good online shops with reasonable pricing?