$600 is enough to hit a ton of easy bonuses. Full Tilt's bonus is not an easy bonus to clear. While waiting to clear a $600 Full Tilt bonus, you will be missing thousands of dollars of other bonuses.
If you can play break-even poker at $1-$2, you can get paid $9/table-hour for 5 table-hours each month at William Hill, TotalBet, and UKBetting, for a total of about $135/month. Bet365 not only has a nice initial bonus, it has been giving out $100 for 500 raked hands at $1-$2 or NL $100 for the past few months.
BW bonus grid