Are there any s2000 specialists that don't charge a million around sydney that could rebuild a transmission?

People have suggested to buy a used one and chuck it in to save costs, but you'd never know how thrashed a transmission was by the previous owner. Not going to fork out money for a mystery box that could malfunction within the first week of use.

I've found a rebuild diy but i'm not mechanically inclined and so i'd say it's impossible to do it myself. Suggestions anyone?

Cheers