Well if a guy says he builds every transmission himself. The operation clearly can not be that big and I think someone just stuck their foot in their mouth. The question here is "How much can a Pig Eat?".
Other options are available is all I can say. Some of these guys on this site never get to finish their cars because they are over paying for things like this.
Here is an Example...$2000.00 for a Trans that will hold 1200+ HP/TQ or $4800.00 for a Trans that will hold 1200+ HP/TQ.. Both built done and shipped to your door for a shipping charge of $250.00...Both have a good reputation for holding up to the power with virtually no complaints to be found anywhere........ Hmmm that is an easy one.
Oh I forgot, overpaying for something is always good.