In regards to trades for services I might be able offer some insight. Now mind you I'm not a lawyer but I do run a side business and have accepted trades as payment...
I train dogs. I either buy puppies, train them then sell them as either started or finished dogs OR I train other people's dogs.
Hunt dog training fees are rather high compared to your run of the mill "I got my dog training degree from the webz" fees. A finished dog can run you anywhere from $3500 to $10000 depending on the quality of the dog and the trainer. Training costs can vary from $1500 on up to $10000 depending on the trainer and what you want the trainer to do with your dog.
My fees typically run around $2000 to $2500 per dog for training from "green" to "finished" depending on how long the dog is in my possession. I understand that today's economy makes it difficult for people to come up with that kind of money. As such I have accepted trades that were offered by people. So far I've taken a car as trade for training services, a boat, 20 cords of firewood and a high end AR-15. I sold the car, boat and wood. I kept the AR. So what am I? Am I in the business of training dogs or am I a car dealer, boat dealer or am I in the firewood business? Better yet am I an arms dealer then because I took an AR in trade for services rendered? I don't believe so. So long as I'm not buying and selling/trading these items for a profit on a regular basis I don't believe that I'm anything but a dog trainer. The majority of my business is still a cash operation but a trade here and there isn't anything to make a fuss about.
This is who we are, what we do.