Sight may be a Chinese knockoff. Those will last a little while before they fail.
Years ago, I put a Chinese made NCStar Aimpoint clone that cost $50 on top of a Saiga 12, specifically just to see how long it took to fail. The answer was “about 25 drums of slug and 00 Buck.”
Also, AR-15s can be had for under $500 now (well, or before the current wave of Bidenflation they were). Even names like Colt and Smith and Wesson.
There’s also the market for the area to consider, as well as new vs. used/pawned.