Association rents common area parking garage to condo owners

I own two units in a large high-rise downtown Chicago condo building and pay $180/month to rent one space in the garage. The garage is a huge profit center for the condo association. $180/month seems to me like "double taxation" since theoretically I own some small percentage of the garage, which is classified as common element. (There is no deeded parking here, but that may be a direction the board should consider.) My question is this: since the garage is common element, can the condo association legally charge more than their prorated per-space costs to owners needing parking spaces?