John Doe wrote:
Any good online merchants that sell the equivalent of cordless drill
motors from 14.4 to 36 volts?

I'd put a WTB ad in my local Recycler newpaper.
**Battery-powered drill wanted. Dead battery is OK.**
Bet you get more calls than you can handle.

Partly out of curiosity.
How much would you pay if you had to buy a motor separately
and needed a motor like the following 36 V cordless drill uses?

You're thinking too linearly.
I always think *surplus* first for a one-off item.

Or would you pay less by buying a drill body off of eBay/wherever
and using the motor from that?

There you go.
There are lots of tools out there that guys won't buy a battery for.