How hard would it be to replace a gasket?

It's extremely easy, a 5 year old could do it.

Getting to the gasket, however, is usually the trick.

I assume you mean head gasket, and if it's your only car and you have no mechanical experience, just get out your visa and make some calls. Don't tackle this yourself if you don't have automotive exp.

just my 2c

A great site to check out the cost of repairing head gaskets is driverside.com - just enter your car into the menu, go into "service your ____" and you can plug in your zipcode to find out how much the part and labor will cost for your area.

Actually, if it is a head gasket, it ISN'T easy. You have to disassemble the entire top of the engine to get to the head so it can be unbolted. Once you remove the head, it SHOULD go to a shop to make sure that it is perfectly flat and straight. Blown head gaskets can really be cause by a lot of factors and head warpage is the most common factor. You will also need to check the area where the gasket blew. Is there a crack in the block near the spot? Is there carbon build up near the spot?? Not a backyard mechanic job if you do not have the correct tools and at least intermediate experience in auto repairs.

If a 5 year old could do it, there would be a lot of 5 year olds in the car mechanics business!