While trying to fix a wiring problem on my wifes 03 Caravan, I broke a capacitor half of the fuse box. The two posts are still connected to the board, half of the capacitor body is gone. I know nothing about these little parts, what could happen if I ran the van? Should I try to match it at radio shack and replace it or buy a new board for $235?

a capacitor in the fusebox ? or on a circuit board ? if there is anything left ? and you can read the value etc. try "radio shack" or "circuit city" or whatever they call themselves now.
I'm not familiar with that car but my guess would be that that circuit is for an accessory like intermitant wipers or dome lamp timer etc. as long as it's not in the ECU itself ? start it up and see what dosen't work anymore. Worse case you'll blow a fuse.

Its on a board under the fuses. All it said on the capacitor was "mexico" so I'm not sure what to replace it with. I had thought about starting it and seeing what did not work but did not know it anything else would screw up. there are only two capacitors on the board.

Short term running with out it should not be a problem. Capacitors are used mostly to absorb spikes in the current/voltage or to smooth out at ripple in the voltage. Adding a cap can lenghten the life of other components by eliminating the spikes. I would try to find a replacement but if it is just a capacitor it should not do any harm running with out it for a short period of time, we're talking weeks not years.

Thanks for the info. I traced the board out to see what the capacitor was on and it turned out to be the rear window defroster. I pulled the fuse so there should be no problem.