That isn't what is expensive.
If you get 10 GB, the question is, then what? I have bidirectional 1 GB plugged into a $200 EdgeSwitch, which then feeds Cat 6 throughout the home ($100/500 feet). This then filters down to $20-30 unmanaged 1 GB switches elsewhere. The whole thing is under $500.
If I wanted to go up to 10 GB I don't just need to change to a $2K~ EdgeSwitch, I also need to run fiber/6E to be able to deliver more than 2.5 GB to any endpoint, then invest in expensive switching infrastructure elsewhere in the home to turn the incoming 10 GB signal into something more devices can accept (e.g. 1 GB or 2.5 GB).
Safe estimate, is to go from 1 GB bidirectional to 10 GB bidirectional, it would be $5K in equipment and pulling new cable.
For $100/month I can do 10 GB, but I won't because of the equipment cost/diminishing returns rather than the ISP cost difference. If network equipment comes a LONG way, and I can do it for under $1K, I'd consider it.