transmission gasket replacement

Hi everybody!
I am writing here because I have the feeling that my Ford dealership is ripping me off. I took my car in for the 60,000 miles service, I have a 1998 Ford Explorer Sport, and they found traces of metal in the transmission fluid. They gave me 2 options:

1- Replace the trans gasket for $272.00 (which I agreed to)
2- Or Take the whole transmission down and replace all the valves for 1800.00

How is that possible? Is that too much to pay, and do I really need it? Couldn't I do it at just any mechanic for cheaper?

Any response would be appreciated...

Thank you

I'd say drive it 'til it breaks. If it is working OK, leave it alone. In the meantime, get some estimates for installing a reman trans. for if and when the time comes.