Ions are no longer made, so you'd be looking second hand, plus the standard Ion setup doesn't have the ability to remove the bolt from the back of the body, which makes stripping for cleaning/maintenance a major pain in the arse. The Ion XE does.
For current guns you're looking at the eNMEy or eNVy - with the envy just being an electro version of the enmey and both having a bolt out back setup. Either would be great for rec play, although personally I prefer the eNMEy as having the electro board in the eNVy just adds cost and a bit of complexity with no real gain in performance.
To be honest, although they'll be usable on the sup air field, neither is a great choice for tournament paintball as they don't offer a Millennium ramping fire mode, for that you'd need to up your budget and look at something like a Planet Eclipse Etha or Empire Mini.
Edit: if you're looking for a secondhand Ion - that one for £100 in classifieds at the moment looks a good buy with aftermarket body/trigger/board plus clamping feedneck and on/off asa - bargain.