IF no ban happens, then prices will return to previous levels...plus about 3%-5%.
My recollection of the previous ban prices is related to an ad I saw in the shotgun news at the time. I was studying SKS prices at the time because I was considering getting one. I remember before the ban SKS prices were around $99 for a rifle. After legislation passed there was a 6 month, I believe, period before the stipulations of the ban went into effect. From the day it passed til the day of the stipulations coming into force, that 6 months, was Crazy Time. SKS's went up to $400. Magazines went up 500 or 600% in some cases. After the ban passed, it was realized that manufacturers could "beat" the provisions on "assault rifle" production by removing bayonet lugs and flash hiders or pistol grips and continue to make firearms that fired semi automatically and used the old style hi capacity clips. So the "ban" did little to stop production of semi auto firearms that could use already produced hi cap mags. Once that was realized, crazy time was largely over. Magazine prices still stayed high, because they WERE barred from producing any new hi cap mags, but as long as you kept new springs and followers in the mag bodies you could refurbish old mags. But rifle prices dropped back considerably.
That won't happen this time. The first ban was ineffective at hitting the guns they wanted banned. They won't make that mistake again. New production semi autos I think will be only for police and military. Some 5 rd fixed magazine sporting 30-06 in semi auto and such might be allowed, but detachable magazine designs I think would be outlawed, or set at the 10rd mag level.
This means that guns which are grandfathered in will not only STAY high, but will INCREASE in price. How do I know this? Because the same thing happened to machine guns when they were restricted. It was a bit before my time but I've heard that you use to be able to mail order machine guns and they were not the equivalent of buying a luxury car. If you can find machine guns now that are less than 10K you are doing well, I understand. If no new AR15's, AK47s etc are being allowed to be made, then the prices on the existing ones can only go up as old ones wear out and the supply diminishes.
So, my opinion, if a ban passes and it followed the same process as last time (it will not, this ban will be far more extensive) prices on rifles and magazines will go up about 400 percent from their prices say a month ago within the first couple of weeks of the ban's passage. I've already seen AR15's go from 800 at Walmart to 2,000 the other day at the gunshow. 2.5 times as much. If a ban happens, expect those prices to double. Or let's use the "400%" measure. AR15's would go to around $3200 each. AK's to around $2000 each. SKS around $1500-1600. And unlike the last ban in 94, there will be no new rifles being made to act as a substitute arm. Prices on these will remain high until the ban is removed and new firearms made. It's a relatively simple concept in economics. Supply--demand.
My personal opinion is that the House a magazine ban is entirely possible, as well as a ban on new production "assault" rifles. Registration, everyone doing background checks etc is the thing the Administration can bargain away in order to appear "compromising". But the ban on hi cap mags and rifles...yeah, I think that is coming.