I would go in for about up to $3k.
I think this is a good idea but it would all depend on what Hitech is planing and why his game is still up and running.
Is he keeping it on to make money or is just trying to break even and keep it running for the community?
Can we buy the server and game (AH3 with the old AH2 H2H back) while Hitech retains the IP and rights to further develop a new game (AH4).
If Hitech ever goes to sell the game IP to some one say like EA I pray to God he gives us a heads up and maybe a chance to offer some sort of counter offer to keep AH3 Going.
Well, I didn't really take the OP that seriously because I thought he was jesting.
There have been a couple of interesting discussion on that over the last year. I think the last one was over in the Wishlist somewhere if you want to find it. We even tried to run some possible numbers.
Basically take what you'd estimate the yearly net income (the hard part to calculate) and multiply that by 5 and that starts to be a reasonable number to negotiate around.
I think the conclusion was there was no reasonable amount of money a VC could offer that I'd suspect HT would be interested in.
It's a long term fixed annuity he as invested in for years so no reason not to let it sit in the closet and run for passive income stream, even if he goes off and does other things as a company or individual engineer.
But if you want to day-dream lets say 1000 subs, I'd be surprised if he would entertain an offer less that ~500k-1mil. He might also have private investors already to satisfy. I don't know if that would make it easier or harder to sell.
But hey, get $500k and wave it in front of him and watch for a reaction. Then you'll know how to play him.

$0.02.