In 2010 tc got commonly sold for 21k/USD
rip inflation
Now that the new torishop prices messed up the market so it's even more slow than before the rates go between 6 and 10 kilo per 1 USD.
Now the opposite is happening, a deflation seems to take place. It's a very bad time to buy tc for the sake of improving your character, if you ask me.
You should wait a while and see if the rates go up again once they fixed the market (if ever).
If you do insist on buying tc now I suggest you just open a thread in the items section on the market. The flies soon will fly by and fight for your money.
Don't take the first offer, always haggle.
Some marketeers will also be willing to give you some items additionally.