Boots currently have their 500ml shampoo and conditioner range on a very good offer of 75p per bottle. In the current in-store magazine, dated Jan-Feb, there is a coupon for 200 points when you buy ANY 2 shampoos or conditioners (excluding miniatures and premium brands). The magazine is free if you're an Advantage card holder. You can get as many as you like. As such it's 50p profit in points terms (£2 back in points) for each 2 bottles you buy.
On top of this, if you look at your Boots app, you can get 100 points for buying anything. This works in conjunction so 300 points (£3) for spending £1.50 on shampoo/conditioner.