Instead of random guesses, show your working

I'm going with 16,000

This century we have only had one attendance higher than 16k and it was against Man City in the FA Cup with 4,600 away fans.

These are the cheapest adult tickets this century and that coupled with the feel good factor I expect us to have the most home fans we've had at a game this century but Crewe won't bring anymore then 1,500 IMO (which is roughly 3x their average normally)

So yes my prediction is a total of 16,000