While risky, you may have to either search for a used netgear R7000 or other high transmit power router.
If performance is not much of a concern, (e.g., no streaming), and if you already have the place wired for Ethernet, then you could cheap out and get 4-5 of those n150 travel routers, and put them in AP mode.
PS, in a $40 price range, it will be hard to find a router that will do better than what your ISP may provide for free (assuming your ISP is not charging a rental fee).