In reply to Shane jones:
> Also would I need to get between 10 and 12 draws just to be safe?
Depends what/where you're climbing. In my experience in the UK it's rare to need more than 10, but more can be better if you end up using two opposed to toprope on. The longer sport routes tend to be harder though, so if you're pushing through the harder 6's you will want more.
In the alps/spain/big sport destinations pitches are much longer, and sometimes you wonder if all your draws will be enough. Then you're glad to have 12 at least. If you have a double set it allows you to link shorter pitches together, which is really useful when you're climbing with a 70m rope up 20m pitches. If your partner brings a set you're all good though.
Long answer short - get 12. And get mostly longer ones, it's rare you want a short draw, but very common you want a long one.