AEGs are problematic, especially V2s at 450FPS or more. And once that is no longer an issue you still need to accurize your rifle. Semi-autos can come in gas just like a BA but you are looking at either blowing a wad of cash or having problems with consistency with a NBB or GBB. BA rifles seem to be fairly priced for what you get, while I have yet see a single AEG manufacturer fix the AOE. Being the biggest problem in the electric market and AOE correction has been mainstream tech work for half a decade now, I'm assuming its another form of planned obsolescence.
I would go with something cheap if you are new to "sniping" but if you have been playing for years and love the M4 system and know that you will play multiple roles for years to come, I'd consider a Polarstar PR-15. $450 for a gasbox, $600+ for a complete PR-15 and another $150 for an airrig. They use AEG mags and you can play every MED on the field with simple adjustments. $600 can easily be spent of two stock AEGs, one AEG and upgrades or one bolt action rifle