Can I get a guesstimate of what it cost to replace transmission?

Thanks......we dropped the pan, found no metal shavings, did this because three times, following a slow down and stop And then a lightly accelerated pull forward, it went, but very slowly, like it was not engaging. Once I put it in reverse and It backed right up and then put it in drive and it took right off. The other two times I was pulling up to a gas pump slowed to A stop and then went to pull more forward and it did the same thing, but then both times took right off and I haven't had a Problem with it since....any other ideas?