I must disagree on one point. Collapsable stocks are not illegal on post ban guns any more than a pistol grip is. It is the combination that you have them in. You can buy an ATF classified "non-pistol grip" - and yes, they do exist - and put a collapsable stock on a post ban. As for the post ban law, you can have a detachable magazine and "one" other bad feature. Bad features are collapsable/folding stock, bayonet lug, pistol grip, flash suppressor. I may have missed one or two evil items, but those are the big ones. The standard configuration is pistol grip and detachable magazine. I'm not trying to split hairs, but there is a way to have a collapsable stock on a post ban AR. Gogogadgets.net has "non-pistol grips". Are they great, no, but you have the stock you want. It's all in what you really want and what you'll give up to get it.
Sorry so long,
jd1