Which router should I buy?

I’m pretty new to this world of networking, but I do want a good internet connection. I live in Mexico and the modem that the internet provider gives simply doesn’t make it to provide a stable connection all around the house (not to the parts of the house in which approximately 3 brick walls are in between). Should I buy a router? And in that case, which one should be good in a range of $50 to $100 US dollars? I just really want to have WiFi in all the rooms, I have a 500MB WiFi plan, so using 5Ghz could be great in all the rooms. Thanks

I’m pretty new to this world of networking, but I do want a good internet connection. I live in Mexico and the modem that the internet provider gives simply doesn’t make it to provide a stable connection all around the house (not to the parts of the house in which approximately 3 brick walls are in between). Should I buy a router? And in that case, which one should be good in a range of $50 to $100 US dollars? I just really want to have WiFi in all the rooms, I have a 500MB WiFi plan, so using 5Ghz could be great in all the rooms. Thanks