You Can Customize an AR???

So I've had my Bushmaster for nearly a year now. I've added a scope to it thanks to Ambulance Driver, and I've purchased or been given a goodly amount of pre-ban magazines. Aside from that, though, it's remained in the same configuration that it was in when I brought it home.

There's something horrifically wrong with that.

The AR-15 based rifles are noted for their modularity - the ability to change uppers for different calibers, change between carrying handle and flat-tops, have different barrel lengths, etc. - and I have yet to take advantage of this strength. Well, that's about to change... There are several improvements I'd like to make for the time being:

• Upgrade the pistol grip. It's got the stock Bushie grip, which isn't the most comfortable grip possible. I like the looks of the Hogue grip (big shock there) but am open to other suggestions.
• New stock. Being in MA, I can't have an adjustable stock on a new semi-automatic rifle without running afoul of the accursed Assault Weapons Ban (fuck you Mitt RINO Romney). Therefore, having a collapsible stock that's pinned in one position makes about as much sense as a screen door on a submarine. I really like the looks of the ACE Skeleton stock, but there's a bunch of other sweet looking stocks out there as well.
• Handguard/forend. Realistically, I just want something I can jam a cheap vertical forend grip on just because I can (and it makes liberal gun-grabbers wet their pants). Something like this, perhaps, that gives me the option of a rail for a forend/bipod, lights, or scout-type scope. However, the Hogue forend looks mighty slick, and is available in OD green as well...
• Flattop upper with a 20-24" barrel. Something like this for more serious long distance work. This is the least likely of the add-ons for now, given that it's by a significant margin the most expensive option.

So many options, so little money - what should I change first???

That is all.