Yes, the price of the Mosin Nagant is going to rise just like the SKS. Here in California, back in the '90s, the SKS went for a $100. Now, my local gunshop will not sell them for under $400. One reason is the balance between supply and demand. Simply put, as they are purchased by Americans, the supply dwindles and that makes the demand greater than the supply. And we all know that's all the market needs to raise prices on any item in a capitalist market. Finally, as the supply dwindles, they became rarer and that is also a reason or excuse to raise a price.
As time passed they became more expensive. Even though people said they were crappy. One reason the Mosin Nagant is underestimated and berated is that often a person doesn't want to admit that a 60 year old, $100 rifle can actually compete with their brand new, American made $700 rifle. We all get that attitude sometimes.
It was just a couple of years ago that the German Mausers were the Big5 $100 weekly sale item and they've become more expensive.
The Mosin Nagant will do the same thing. As we can see, it is already happening. I say, get a few of them at $100 while the getting is hot and save them for ten years and you will double your money on each one, at least! I said it, and then you just take a look at this forum posting ten years from now and remember I said it.