that would be fine if you want to do it, the one thing I would advise is that 450 commons/uncommons the only effective way to ship cheaply will be a bubble mailer flat rate envelope (if you make say 5 stacks of 90ish cards each it should be safe or 4 125s whichever), even then it will still be around $5.80 but I think 450 c/u will actually exceed 2 pounds in a box, if my estimate is right, and that would get pretty expensive for both parcel or priority! but the reason I say all that is that it might add like an extra week to the trade as you wait for the bubble mailers, it is free but you cannot just pick them up at a post office and would have to wait