If you want 10 litres of Dulux paint, you'll find it hard to beat this price currently.
Homebase have a buy 1 get 2nd half price offer on.
You can mix & match.
You can get £5 off £50 http://www.moneysavingexpert.com/deals/homebase
- which if you needed 20 litres would give you a price of £49.
2.1% TCB/ 2% Quidco