Its been a year since I autocrossed and w/ a different S13 now.Anyway, its $25 for SCCA members, and $30 for non-members.Even if you're not sure you can come, please pre-register (no fee) at http://www.myautoevents.com (you can look up autocrosses by state/city)
Directions:
From Delaware, Commodore Barry Bridge, or I-476 get onto I-95 North. Exit at Ridley Park, Exit 8. (one exit north of 476) At the top of the ramp bear right. The first light is Boeing, turn right into lot.
From Philadelphia, New Jersey (Walt Whitman, Ben Franklin, etc.) take I-95 South. Exit at Ridley Park, Exit 8. Turn left at light at the top of the ramp. The second light is Boeing, turn right into lot.
More info and such here:http://www.phillyscca.com