I have Tarozzi rearsets on my 550....while I could "technically" fit passenger pegs behind them, there would be no room for the passenger to put their feet. If you want cheap, that's not the way to go anyway...they are pricey.
Have you looked for a set of CB400 pegs (from the earlier bikes)? I've seen posts on here where folks have put them on their 500/550's with success. They are a "mild" rearset and keep a stock look. You may have to fiddle with your brake pedal (or replace it), but you'd probably have to do that with other rearsets anyway. Might be worth looking into. You can find them on eBay as a set every once in a while.