Fixing a bad head gasket myself

I started a head gasket job on my 93 grand prix 3.1MP motor. I've gotten all the way to the head gasket and they are bad looking but probably what is expected. I've drained the oil and am now starting the rebuild process where I'm getting a gasket set from Auto Zone. Does anyone know a cheaper spot for the gaskets? Also I've read a few posts and there talking about replacing head bolts because of there torque to yeild ratio. i was just gonna keep all the bolts I took off and use them again. My mechanic does not see the problem with this. He also thinks that torquing the bolts aren't important either. So could someone give me the specs on the head bolts and what bolts should I get new and from where if possible. Also, do I need to replace the exhaust manifold gaskets. If anyone has any suggestion feel free to let them be known. T.I.V.