Good Luck
Televideo terminals and parts for them are pretty scarce. Surprising, since so many of them were made. Low supply probably signals that people are holding on to them, and still using them, in contrast to the scarcity of early Wyse 50 and Wyse 100 terminals which is more due to poor reliability, and low number of operable units.
If you can accept a Televideo compatible, and are not set on a actual Televideo terminal, there are lots of Wyse terminals, and companies that specialize in reconditioning terminals. Recently, I've been buying some new and used Wyse terminals terminal since they are easier to find than Televideo terminals (or the Ampex terminals that I actually prefer).
I got a couple of new Wyse displays components without keyboards, and it took me four tries (four purchases from four different Sellers) to actually receive keyboards that work.
If you can find some working Televideo keyboards, I'd expect the price to be higher than $20-$30 each. Be ready to pay $60-$70 or so. You can find complete working Wyse terminals for the same amount of money or less.