Where do you see the amount of tc you need to pay for the flame you make?

After you make the desing of your flame, click on "create" button.
It will lead you to the tb forum and it will say:
"Estimated cost for flame my zawesome flame --- TC you currently have -- TC"
And bellow that will be a button saying "forge"
If you have enough tc you can click on it

The minimum price for forging is about 66k.