My ISP doesn't provide a modem or router because with them you can take an ethernet cable and plug it straight into the wall then plug your laptop into the other end.+1 on speaking to your ISP. I'm not usually pushing that direction, but for your price point anything you buy isn't going to be an improvement on the ISP provided hardware. And in most cases, I believe ISP provided hardware DOES allow you to remote in and set up a basic guest SSID.
If all you're looking for is more control, I have an old DLink DIR-880L you could have for the cost of shipping. But I haven't even plugged that in to test it in a couple years at least, so I'm only guessing it's still functional? And I'd say the only way that's worth it would be to flash it with DD-WRT or Tomato. Even then, it's pretty old hardware. (EOL in 2020 it looks like)
The only reason I need wifi is for my mother who likes to use her laptop to watch things on youtube and surf the net a bit and that's why I don't need anything special.
I'll keep that in mind about the router that you have,I think I may have already found something.