You'd need the mount's for the shifters, which are a fair bit usually. And you wouldn't need the front mech as it's top pull (I think), plus the Ultegra 6600 one you've currently got on will probably do the job better.
Have a look at these/try and win them, the pair I messaged you went for £10posted so these won't go for much more, they've got the clamps already so you don't need to worry about that.
Then you can choose any old Sram 10 speed rear mech, road or mtb; doeable for a tenner depending on which level you choose. Will be much cheaper than buying that mini group
And like fredycro said, keep the crankset, chain, cassette the same, sell the 6600 shifters and rear mech and you'll make profit.