Welcome to the wonderful world of fast paced technology development. If you're going to play games on a computer, expect to spend money to keep up. AH is THE reason I upgrade my system on a semi-regular basis.
Still, as mentioned, in the world of current games, AH has far less hardware requirements than most. HT and crew have done a great job of providing strong and enjoyable game play without requiring a top-of-the-line system to do it. Hell, this game is even playable on a dial-up connection! Can you say that for most of the online games out there today?
Does high end equipment make things better? To some degree, yes...but if you are willing to understand those differences, it doesn't really take away from game play if your video card or processor can't handle 6x AA, maxed out mip-mapping detail and so on. Even with lower settings, AH is perfectly fine and completely playable at a competitive level.
Of course, everyone has their threshhold of what is considered "too much" for a hardware upgrade, and that's understandable. $80 for some might be nothing, and completely out of the question for others, but bottom line is, you can upgrade to decent hardware that will play the game well for not much money. Birthdays and Christmas are excellent opportunities to get yur system upgraded. For that matter, if you want that new video card bad enough, go mow some lawns, or find some odd job you can make some cash, or start stashing a few dollars here and there...pocket change in the jar, etc. It adds up quick.