My mum found this in one of the Sunday magazines:
1 chopped banana
100g frozen forest fruits (strawberries, blueberries etc.- can buy 500g from Tesco for under £2)
100g fresh orange juice
100g skimmed milk
4 tbsp low-fat natural yoghurt
1 tbsp honey
I added 30g whey protein aswell but that's optional depending on what you're looking for.
Honestly, it's one of the nicest things I've ever had! And if you break down the price of everything, not so expensive either.