See your "collection" as being in a few years--not only what you have now, but will definitely try to get in the future (kind of a realistic "wish list")?

Let's assume that you will retire in 5 to 10 years on a fixed income, so you probably won't be able to buy what you want after that (you can trade if necessary, but not do any impulse buys).  Further, let's assume the laws remain basically the same for the next decade--no new bans or retractions of current bans.

For myself--
I anticipate getting/trading for a couple of different MG's.  Realistically, I would like to have an MP-5 (have the 94 as a sear host now), an SAR-48, M-16, and possibly an AK-47.  I have some MAC's that I will probably use as trade goods, and will keep the full auto FNC I have now.  

I will also get another .50 cal rifle.

I am relatively flush with semi-auto Sport Utility Guns right now (although you never know when something will crop up).  

I definitely need a nice Over/Under Shotgun, and a few revolvers to round out my "standard" gun collection.  

I am kind of toying with the idea of a supressed (or separate supressor) for a .22 either on a 10/22 or Mark II (or threaded barrels for each).  I do want a supressor for the MP-5 when I get it.

Other than that (and, of course the impulse buys that inevitably happen), I think I could be content (there is always ammo and mags to buy!!).

I don't want to forget the possiblilty of getting the AR15.com Limited Edition guns for each of the years to follow.