Pretty much anywheree that sells auto parts.
I prefer Victor/Reinz over Fel-Pro - but Victors are harder to find.
I also tend to prever the cork valve cover gasket - which is very much a minority opinion around here.
Tips:
1) When using the cork valve cover gasket, try to get a tube of LocTite #518 Gasket Eliminator as well. Clean the mating surfaces well, coat both sides of the gasket with the Gasket Eliminator, set in place. Install the screws finger tight only - go have a sammich. Come back in 45-60 minutes, and torque to spec (I think it works out to 5-7 pound-feet. The torque values should be in my Tech pages - link in sig.) Screws for the earlier cast aluminum valve cover are 1/4"-20x1-1/4", and the later stamped cover should be somewhat shorter (probably 1/4"-20x1")
2) Whatever your model year, use the 1996-up oil sump gasket. It's one-piece moulded rubber, and therefore easier to handle than the earlier four-piece bit. It should require no sealant. Torque the 1/4"-20x1/2" screws to 7 pound-feet, and the 5/16"-18x3/4" screws to 11 pound-feet (treat this point as important.) The 1/4" screws take a 7/16" wrench, and the 5/16" screws take a 1/2" wrench - there are only four of the latter, two at either end.
3) Before you start to remove the old rear main seal, drop the new one in a bowl of clean engine oil. Let it soak there until you need it - it will make the sealing lip and rubber overmould more pliable, help it seal more quickly, and make the thing easier to install. The old one can be removed (lower half) from the rear main cap without too much trouble, the upper half will need to be driven out. It's rubber overmoulded to a steel wire core - I use a 1/4" brass drift punch (won't scar the crank) and a brass hammer (any non-steel and non-rubber mallet will serve) to get the thing started. Once you can safely grab it with a pliers, pull it out. The new upper half can be started and installed using finger pressure - just make sure you get the lip facing the right direction! The open side of the V should face the inside of the engine assembly (or else it will leak - and have nothing to do with the seal proper.) Service manuals vary on whether or not to use sealant to seal the ends of the seal together - I do not. Soaking it in oil makes it pliant enough for the ends to seal to each other, I've found.
4) While you have the valve cover off; remove and clean the CCV baffles - helps keep blowby down.
5) Clean out the oil sump while you're there. You'd be amazed at what can accumulate under there...
That's all right off the top of my melon, but it should give you more than you were thinking of before.
