Hey brother, I'm yet to begin playing BAL, so I'm not exactly clued up upon the shop items for the mode. I've only really been playing Master League. I imagine the items will be similar though, and there are some that last just 1 season. I wouldn't be able to give you a definitive answer, so I'd recommend looking through our "PES 2013 Become a Player" sub-forum. Here is a thread from within that forum that may help you -
http://www.pesgaming.com/showthread.php?t=91931
If this doesn't help, then simply create a new thread within the Become a Player section, asking for advice, and I'm sure there will be regular BAL players available to assist you. :)