Depends on the situation, if mates come over EVERY week instead of going to the pub, then fine, chip in a few bucks each. If it's a one off, then hell no, money shouldn't be changed hands. I give some of my mates at work a stubby here and there to just taste and love thier feedback, wouldn't expect one cent for it. But as OP they are going to his house EVERY week instead of the pub, I would appreciate the few bucks for the brewing costs too. I also brew for the love of it and hearing my workmates say "this is bloody nice". Just saying it depends on the situation, as long as you don't have people coming over at all hours to buy a 2 litre bottle like the other guy busted a few weeks ago.