I would do the bushings first, for regulation purposes, you can gain a lot of feel and grip just by reducing suspension "flex", and it wont force you into a new class in autocross.
Plus, unless your familiar enough with the different springs to know whats best, you can have time to ressearch that before you put them on. Also, suspension bushings can be cheap...so it may help you to budget things. You really cant go wrong doing either things, as long as they get done
if its "one or the other, not both" I would do the springs and shocks.
-chet