These 1/72 scale Radio control tanks are on ebay for ~ $20 U.S and are quite good for the money and if you can do a little work, make a great low cost radio system for your 1/35 scale AFV's. I added about 5 connectors (micro 1.5mm) so that it is PNP with my model tanks. I presently have this radio installed In a M10 as seen here.
It has a 2 wave engine\track sound, main gun firing sound with chassis recoil, Demo mode, Sound can be remotely turned on\off, has L\R tracking trim! This is a nice feature that is uncommon on any radio system. Has L\R turret control as well.
Features of this 1/72 scale radio system...
It is 1s 100 mah lipo powered and comes with on board TX charger.
The 1/72 Tiger model is pretty good as is out of the box but is pretty fast for a Tank. The two speed control has little effect on the core less motors is the only disappointing thing with the Tiger as it comes from the box. Also the Transmitter has no on\off switch and runs the expensive AA (x4) down after a few weeks of non use. I added a On\off switch to mine or you could remove the batters when not in use but other than that its a nice Toy as it comes. Kids will probably like it as is.
Of course I am only interested in the radio system its self
M10 Video
https://www.youtube.com/watch?v=BOacyCLYjBY