Yeah, 40% of a 250 GB connection works out to about 23 MB depending on how you define month. May I ask what would happen regarding TOR?
Thanks for checking my math! I used 31-day months, since I assume that is how ISPs do the bandwidth cap.
RE: what happens with Tor:
Run a full node (or better, several full nodes) that is connected to the network directly-- not via Tor.
But to keep your transactions private, you broadcast them through a Tor-connected SPV (not full) node. If you are mining, broadcast new blocks the same way.
That gives you fully-validating-node security plus transaction/block privacy. You could run both the full node and the SPV-Tor-connected node on a machine at home; to the rest of the network your home IP address would look like a relay node that never generated any transactions or blocks.
If you live in a country where even just connecting to the Bitcoin network is illegal (or would draw unwelcome attention to yourself), then you'd need to pay for a server somewhere else and administer it via Tor.