I think the 10sx have a module on the back (Richard might confirm).
In this case, the change to 2.4Ghz is as easy as swapping the module.
Frsky do one (sorry, I insist on them, as I use them)
Corona :
JR :
Spektrum:
Assan:
Jeti:
And many more! (MPX, Graupner HOTT etc etc)
The only thing to be aware, is that when you go for a system, you are attached to it, as a receiver from A, will not be compatible with B etc etc.
Also, the price of receivers etc is dfinitively to take into consideration!