Maybe the color burst frequency is really the one to go for. Not only cheap crystals, but also kits are available. And here comes the latest thought: Using the "Warbler" with an audio source, e.g. Eddie's XORgan or some software.
Bonus here, when not in transmit, the Warbler can serve as a grabber receiver.
I would however, for QRSS purposes, pull the local oscillator below the crystal filter. The latter should be slightly differently loaded in order to bring the response somewhat to lower frequencies.