As a business man myself I totally get and agree that all businesses must charge for services rendered....this is not an option if you want to stay in that business, period, end of story. However, it sure would seem like the "better" business practice would be to simply charge a fee to get in the pool and not worry too much about where somebody bought their gear. Instead of penalizing a potential customer for buying elsewhere, why not charge for the actual service rendered and have no room for misconceptions or arguments??? You don't get/keep customers by right off the bat upsetting them. Customers are like money in a sense...easy to get, hard to keep.
If using the pool is an issue then charge to use the pool, don't jack somebody for testing a brand new reg just because you didn't sell it. It would seem like the prudent thing to do is figure out why the guy didn't buy it from you in the first place, correct the issue if possible and maybe then the next one will.
Our LDS is fantastic and I really wish I could have bought all my gear from him. He may not be the nicest guy in the world, but I am pretty sure he is at least in the top five. I feel bad that I didn't get everything from him, but two of the brands I wanted he is not a dealer for. He has never mentioned or implied any issue about it at all. The result??? I send everyone I possibly can to him and I buy every thing I possibly can from him. Now, if he required me to have the fins I bought elsewhere "inspected" before I came into the store....the last item I bought from him would indeed be the last item I bought {from him}.