Simple solution - Steve Ralphs longbows. (
click here) Really great guy, very understanding to deal with, and extremely knowledgeable. I bought my son's longbow from him earlier in the year (tri-laminate, horn nocks etc) for around £200, but his range of sycamore self bows start at around £75.
My nipper's bow was made to order, (so it should last him 3-4 years), so it did take Steve about 6 weeks to make, but I believe he's got 'off the shelf' stuff available.
I can highly recommend his products - he even made the arrows too.