CRW Airsoft, an airsoft retailer that imports from China and sells in the UK and Europe, has in stock the DBoys SPR Mk12 Mod Full Metal.  This is a hefty looking rifle from DBoys and if you want a sniper loadout with full-auto capabilities, then this is the rifle you need to purchase without breaking the bank. It is TM compatible so you won't have much problems in using your existing M16/M4 Magazines.

Included in the package is a sniper bipod, 200 round hi-cap magazine, 8.4v 1500mah large battery, charger, metal handguard, sniping motor grip, and 1 piece RAS to attach sniping or aiming accessories for it.  It fires at 350fps with a .2 bb and is priced at £135.99 (US$273.27/ €201).