Cheap 2.4 digi sytem

[DaveG28]

As I have an intermittent fault on my extremely expensive radio gear, rather than buying again I'd rather get an emergency backup in case of disaster!! So I was wondering if anything cheap fits the bill as below:

1. Digital (I use digital servo's so assume I need this?)
2. 2.4ghz as it's hassle free
3. Has subtrim
4. Preferably model memory but not necessary
5. Cheap cheap cheap

Anyone know what fits the bill? How about the core system, is the latency terrible (I mean really bad rather than just slightly slower), is it reliable?

Any other ideas?