I don't think there is really a minimum (from the mental side, not the embarrassment side...), as long as the wallet and the wife allows. When the US Open was under Barry, a few 400 level players would play every year. Put up your money and go experience it. Might as well start with a professionally run MR event, if he aspires to be on the "tour".His airfare could be as low as $250. The hotel is about $200/night for three nights minimum. Entry is $250. I think it could work if he wanted to go to Orlando for some other reason.
For a pro-level event, he might be better off going to DCC which is only a five hour drive for him.
What FargoRate do you think he should have before trying either of those events?