£33.99 for GTA V & Megalodon Shark Card Bundle PC digital download - limited to one per customer (no region lock)
Note Rockstar social club version (not Steam key)
Note you will receive one key, a separate code is not provided or required for the $8,000,000 Megalodon cash card just redeem on a new Rockstar account.
Base game and other shark card bundle versions available from £19.99 see here
Same bundle is £33.24 at cdkeys.com after facebook like, but if you have credit/reward points Game.co.uk might be better option.