[fysiks]

Even if it is a home server you should look into using sv_downloadurl. If it is downloading directly from the server then, likely, your internet connection speed is not the limiting factor. I have my server hosted at home and I use a webserver hosted on the same machine for fast download and it works fine. If it's still slow at that point you would want to get webspace and use it OR upgrade your internet connection.

Bottom line: Use the sv_downloadurl even if you have to use a home hosted webserver. It won't be the fastest thing in the world but will be much better than getting files from the game server it self.

There shouldn't be a need to "buy a new game server".