I've now got a version, including antenna coupling, using tubes that
can be purchased for 1 buck each from various online sellers in their
"Dollar Days" listings.
In addition to 'cheap' the 6KE8 has an impressive gm of 12000 so
sensitivity is excellent and small MP3 players/cell phones can easily
drive the transmitter. Actually, I don't think the gain pot is needed
anymore but it's still on the breadboard so I show it.
http://flipperhome.dyndns.org/FM%20Stereo.htm