Have you seen this post?
Please don't give TNBTC to people who are just hoovering it up to paid by defi scams based on it.
Real testing just needs tiny amount, the people who "need" large amounts are selling it. (technically trading it for defi testnet defi tokens which they expect to get converted into real value once that scams they are participating in go live).
This abusive and anti-social behaviour has made it hard for people to get testnet for actual bitcoin testing because they've drained all the faucets and conned the people that have historically given it out out of theirs.
It's also forcing bitcoin development to abandon testnet for testing.
Your calculation on the cost of mining Testnet
0.001 BTC/tBTC shows the system isn't working anymore. I don't get it: why would anyone spend that much money on mining tBTC anyway, increasing the hash rate to rediculous heights?