2001 Pontiac Aztek blown head gasket question?

[ScareCrow26]

So I have this Aztek with a blown head gasket. I started calling some shops to get repair estimates, which ranged in the $800-$1000 area. The last shop I just called was an engine shop nearby, and they told me something which no other shop told me. I just want to know if they were correct, or if I'm being BSed. He asked me if I had signs of antifreeze in the oil, to which I replied yes. He said that the antifreeze in the oil will cause the engine to corrode, and that the head being milled down would cause more stress on the other engine parts. He said his shop would not do just the head gasket because in a few months to a year the piston rings would have to be replaced if they did it that way. He would only quote me the price for a full engine rebuild, or replacing the current engine with a new or used one $2400-3500 depending on what we decided to do. Now I know the entire coolant system needs to be gone through to find what the cause of the blown head gasket was, but the entire engine rebuilt? I would like some opinions from some people who know a little more about cars than I do. I know of several people who have had head gaskets replaced with no further problems, and I think this engine shop is just trying to get more cash out of me.