I've tried many many shampoos in my quest to reverse the effects of years of swimming and ballet buns. So many leave residue or fail to adequately nourish the hair. Whilst I don't think you need to fork out a fortune, I do think it's worth spending pennies on natural, organic ingredients and avoiding parabens and SLS.
Fifteen years (yes fifteen!!) in the making Liz Earle's Botanical Shine Shampoo boasts shea butter, vitamin E and apple and orange blossom extracts. It has a lovely milky consistency, smells divine (like organic baby shampoo!!) and a little goes a long way. My hair smells lovely (in a natural way, that makes people think you just ooze floral loveliness from your pores), is soft and gorgeously shiny. I've already popped into the Duke of York Square store in London to pick up a second bottle well before the first will run out! At a mere £7.65 for 200ml and the option to save on bulk buying or combos (as with all Liz Earle products) and the Liz Earle freebie with every purchase, it's definitely a good buy!!
As a rule of thumb, use about a blob about the size of a 10p coin for shampoo and a 20p for conditioner.