With per diem currently at $2.10 that's 396 hours TAFB per month. The average hard line seems to have about 250 hr TAFB or so. I suppose $10000 per diem a year is possible for a line-holder but you would be picking up pretty much all the open time you possibly could on days off with as much time away from base as possible. It would still be pretty hard to pull off for a line holder and probably wouldn't be feasible for a first year FO spending 2 months in training and a minimum of 4 or 5 months on reserve.