I would buy a gift for the 8yo and a litle something for her sister. My thoughts are set a budget and then divided it accordingly. I agree with BONKERZ..... crafty things are always good as I find most people will not give these type of gifts (prefering figures, games or dvds!).
Anyway, don't worry too much, what will happen is the birthday girl will tear open the gift say how lovely it is then quickly move onto the next!!!!!
Why does my dd get an excess of crafy stuff . she loves it but it makes me break out into a cold sweat. True, now age 6 she is able to do a lot of it with minimal input but,there is only so much craft one small girl needs.
nb: I think we must be being given the nation's 6-8 yr old's share of craft gifts!
But yes, crafty bits or book tokens are great ideas.
Dilemma456, if you havent already invested in presents for the birthday girl and her sister then i have a suggestion for you. I came across a website that sells paint your own t-shirts and they were the best i have seen. Lots of varieties are available eg mummy and me, my family etc. The kids get to paint the clothes and the appropriate skin colour tones, its brilliant, my nephew loves wearing his and he took great pride in painting it. The website address for the t.shirt is www.ofcolour.co.uk take a look anyway and then you can decide. Hope you get sorted.