If it's just a matter of the seam having pulled apart by an inch or two, then it sounds like a pretty simple fix---something a seamstress could do in a few minutes for a few bucks. Or do you have a friend who sews? He or she could probably fix it either by hand or on a machine.

If the hole is at a place in the seam that will get a lot of stretching, be sure to use a thread that has a little give to it so you don't break the new stitching when you pull the jersey on or off. A good seamstress should be able to select the right thread and tension just by looking at the hole and tugging a bit of the intact seam on either side of it.

Good luck!