I know this might be irrelevant to the OP since she lives in the UK, but for US residents, MAC items are cheaper at the CCO. (CCO is the Cosmetics Company Outlet, basically an outlet for brand name makeup like MAC, Bobbi Brown, Clinique, etc. CCOs sell lots of stuff that are from discontinued lines, like limited collections, etc.)
I heard that stuff is generally 30% cheaper than retail:
Glitter eyeliners: $10.50
Eyeshadow pots -$9.50-10.00
msf-15.75
nail polish-7.00
brush sets-33.75
fluidlines-11.75
pigments-13.75
select spf-17.50
studio fix-18.75
paint pots-11.75
lipglosses & lipsticks-10.00
shadestick-11.75
mascara-7.50
Brush 187 - 29.50
Fix+ - 12.00
Blush - 15.75
Unfortunately, each CCO carries different stuff. Sometimes, it's a hit or miss. I was at the CCO in Primm, Nevada earlier this month. I wanted to grab some brushes, but they didn't have any at the time. So I bought the 2006 Stylistics Sheer Mystery Powder in Model Chic for $31.50. It retailed for $45, and comes with a refill compact!
I have 3 CCOs near me in Northern California (each about an hour's drive away), but haven't had the chance to check them out yet.
