Yes, but flying on the same attitude as airliners requires from
sailplane similar comm. properties.

So I guess... that 8.33kHz radios are in the range of 4-7k USD?

I'm not convinced, I've been given pretty high clearances.

Anyway, prices seem to have come down. Funkwerk e.g. sells the ATR833
for 1700 Euros (ca. $2050): http://tinyurl.com/2wu78ps