It is not gouging. It is the price for a " buy it now take it now" AR-15 lower.
There is a bubble in AR-15s, M14/M1Aicon, and other mag fed semi-autos inflated by worries of an AWB. There will be orders unable to be filled if and when any restrictions are enacted. If you had 100 stripped lowers in your hand, you would not sell them for $100 each either, and neither will the retalers. You can buy a lot cheaper, but you will have to wait in line. That is the difference.
The demand has even increased the prices on items that cannot be delivered. These prices are and will always be what the market will bear no matter what the product is. It is the law of supply (availability) and demand.
The manufacturers cannot make them to outpace the demand. If they could they would do so at the risk of loosing the investment in higher production, and the surplus. Try to buy a lower and insist that it be delivered next day air. You wont get it for $125.