I am sure it's worth all of the $5 you paid for it ;-)
It's the sort of keyboard that's not worth a whole lot, but really useful for adding to our collection of knowledge. I have to be careful otherwise I'd end up wall to wall of such keyboards, like on those TV programmes about hoarders ;-) It's like my Neve Necam 96 keyboard: horrible to type on, and utterly useless, but it was the doorway into finally learning the difference between RAFI switches and Cortron/Devlin low-profile magnetic valve switches. That in turn was my way into getting in touch with Devlin and learning even more knowledge. I don't begrudge the money I spend on useless keyboards as it's part of our communal learning process.
Ideally you'd have an opportunity one day to compare those BTC keycaps with "real" Key Tronic keycaps and see if they actually are the same. The "&" is the chief giveaway — it's the same weird shape with both Key Tronic and your BTC keyboard.
Also, the controller chip and other chips should give you a rough idea about date of manufacture, and maybe some idea of whether these overlapped with Cherry MX mount switches or whether this was the old design. The FCC ID final action date is well after Cherry MX switches came out, but around the sort of time when you started seeing Asian boards with MX switches in.
