I would recommend the GT3B even at its normal $50 price as bring the best bang for the buck system. At $40, it's a no brainer. Damn good radio, and receivers are as cheap as they come at around $7 each if you buy 5 at a time. Individually they are around $10 each.
No idea, but you can get the GT3 right now for the same price which has a 10 model memory.
HOBBYAMTE Flysky FS-GT3B Rc Transmitter Receiver 2.4Ghz 3 Channel, with FS-GR3E Failsafe Receiver https://a.co/d/6opEi71