A nice amount of dosh, better than the 'I've got £100 and want a full set up yes please'.
Well, the eblade cockers are in the price range, staggered at how cheap they are at the moment, even ex-nexus ones. They are good, especially if you like to fiddle a lot with you gun.
If you are looking just to get the marker out of the bag and blat away and not have to do much to it I'd suggest an Angel: A4 or even an 05 speed are in your price range there and there are a lot of the latter about in the classified section at the moment!
Bit of a different tack is a DM4. I got one after my first electronic marker (angel 04 speed) and man it's lovely! If you can get one with a Tadeo board in and CP roller trigger all the better (standard trigger was horrid for me). It's small, looks sexy and is really gentle on paint meaning you can fire nice fragile stuff that breaks on everything. I got mine for £375 with all the extras mentioned above. Just need to remember to lube the bolt with grease after every use so the orings dont wear out.
Ions- not used one but I'm suspicious of something so fast yet cheap in comparrison. People swear by them while others can only use 4 letter expletive words.
But you've hit the nail on the head: try them out. Some of them will feel just wrong (05 speed for me) while others feel like a 3rd limb. I believe you can get used to firing anything, but some require less work.