The only "kit" that most people on this board will advise, is the Mugen one.
Try to keep the rice dial as low as possible (pointless "air vents" and curves are just ugly)
But, style is completely your choice.
The short answer to body kits, is you get what you pay for. If you want to go cheap, and end up replacing countless pieces, go with fiberglass. If you want durability, and long-lasting looks, go with poly. If you want an extremely durable kit, go with carbon fiber; however, it is VERY expensive.
as for sites; google is your best bet.
Wings West, VIS, and Seibon make some of the more durable kits.
If you just want to see what styles out there, andy's auto has a decent photo gallary:
97-02 Honda Prelude Body Kits at Andy's Auto Sport
One other note- the ebay kits are about 99% crap. they charge $400 for the kit, $400 for shipping, and you end up with a kit that will fall off before you can drive to the paint shop..
just my -0.02.
V/r,
Mike