I have small video transmitters 8mm x 8mm x7mm in size with output power 9 mw @ 9 volts DC, it weighs about 3 grams
provide e-mail and I will send you more details. I make these for some of the specialty distributors in 906 mhz, 915 mhz and 433 for the ARS users
As for a schematic for this, at this size, the component values would be different for every layout and you need expensive analyzers to tune it up properly, even the antenna length will mess it up if its wrong
MS