go into any afro carribean hair and beauty shop-there are lots in london, (brixton-atlantic avenue) and one outside seven sisters staton, where they do a full range of european hair (human or synthetic) in any colour or length you want, for about 12" hair would cost aroung �11, 18" about �15 and 20" about �25.
This hair can be glued in to your own hair-the glue costs �1 (dont worry its hair glue not normal glue) and it wont fall out no matter how vigourous your dance routine is, unlike the clip in extensions which are way more expensive- a total rip off and they can fall out. The glue is made of natural latex and can be removed at any time with the glue remover all sold in same shop (cost �1). or by gently pulling the hair after putting in some hair conditioner. Wash your hair as usual after.