for small fundraising campaigns, especially for those not linked to a nonprofit, it's good to have a specific goal or a specific reason behind the fundraising.
keeps things transparent and above board.
transferring funds as a way of "paying back" for service opens all kind of doors relating to the potential for tax and insurance liabilities that we would all rather keep shut.
small transfers of money here and there are one thing, but once you start to hit five figures, you move into grey areas that are potentially very knotty.
I have a little bit of a background in this stuff and these are the types of things that keep me up at night or give me nightmares when I think about them too much.