Radios are like alot of things. My $.02 would be buy the best you can afford. WHATEVER YOU BUY, keep it in great shape and keep all the original packaging and documentation. Then you'll have something worth selling when you're ready to step up.

I started with a SkySport 6, then to a 6XA, then an 8U and finally a 9C. Those previous radios all sold well enough to make the upgrades possible.