Do you know any reliable supplier of dilithium?

I’m building my own federation starship (Constellation class). I’ve just finished making the outer hull out of Duralumin and plywood. I’m thinking of using lava lamps and duct tape for my warp core. It was much harder to build than my impulse engines (powered by the diet coke-mentos reaction).
However, my starship wont even leave drydock without atleast 5 isotons of dilithium. The best I can get is tricobalt from the local pawn-shop, but it can only get me into a decaying orbit.
If anyone knows a supplier of dilithium, or an abandoned mine somewhere, let me know.

I’m told the Klingon penal colony asteroid Rura Penthe is now abandoned but still contains significant quantities of dilithium ore. It’s only a couple sectors outside the Federation border but of course if you don’t have enough to get out of orbit it’s going to be difficult to get there.