I don't blame you for worrying about this--it seems questionable. I'm not against this kind of trade in all cases--and this is just my opinion, which is all I can offer here--but I am against suggesting it after the fact, after the work is done. That's what I gather has happened to you.
Do you take it? Hard to tell from the outside. You be the judge of the relationship, the long-term value of it. If you establish the rules right now, and reject the offer of trade, will you be better off? This is a guess you'll have to make. No outsider can tell you for sure.
Question added to topic Grow Your Business • April 6, 2008
Does it make sense to accept services in exchange for hours I've worked?
I recently started an IT consulting business and have joined with a phone communications company. The phone communications company has given me several referrals for which I have worked about 82 hours. The owner has done a few wiring jobs for me and wants to trade those services instead of paying me. He already gets 50 percent of my hourly pay for all of the referrals and bills these customers directly.