I like 0.3g Devils for sniping - they're better than King Arms 0.3's, Blaster 0.25's but in an AEG with an inner barrel of 6.03mm or bigger, I don't think it makes much difference what you use, apart from Z1's about which I've read several people less than pleased. I've used about 40,000 BB King 0.2's - the cheapest 0.2's i could find and i promise you, they performed similarly to Blaster 0.2's - about 2-3m less reliable range iirc, but no significant increase in the number of 'fliers' ie BB's that freak out and make a bid for freedom as soon as they're out and about in the air. I don't remember them being significantly worse for grouping accuracy, if any worse at all.
But yeah, for my 6.02 and 6.01mm TBB's I only use BB's with a better rep, like Blaster. So where are you getting them at that price and how much is the P&P?