Have you re-enlisted already? Most infantry MOS's are in high demand because they have a high turnover rate. There more often than not are many bonuses available, but the recruiters are often less than forthcoming with that information.
If you did not enlist already, go in and talk to them and ask them straight up if there is an enlistment bonus for prior-service soldiers in the infantry MOS's. If they say "No.", get up and leave. They often change their tune immediately by saying "we'll see what we can do". More often than not, they'll come back with a "We found one."
If not, try to enlist at the end of a fiscal quarter (October, January, April and July are the beginning of each new quarter.) Designed to meet quotas, enlisting at the end of a fiscal quarter where they are desparate to hit their numbers, you'll find better deals.
Do not sign any paperwork without that bonus, and stay firm in your resolve on this matter.
Good luck. (You may get lucky and get an assignment of choice for the first year as well.)
The Boz