300 Gran seems very fair to me. $2.50 is not a lot to enter a tournament, and the lads and lasses that work to bring you this game need to make money too
. Now, obviously, people who don't and won't buy Gran won't get into the tournament (unless they have been saving up for something else, like a booster pack). People who didn't think they would but want to get into this tournament might be convinced to make that step and buy Gran (and like I said, money needs to be made. This first step is rather important). People who already buy gran will be in.
The only gripe one could possibly have with the price is that they didn't give those people who do not wish to buy gran enough time to save up with Mirage Master and rankings for the tournament fee so they could join. But there are rather a lot of counter-arguments against that, not in the least the one which says that they would lose the gran-sales from that second type of person described above.
When all's said and done, I believe joining the tournament is a priviledge, not a right. We already get to play a damn good game for free and it would be childish (not to mention naive) to begrudge the owners and their employees a healthy profit, something that ensures the long-term existence of Alteil.