What other kit have you actually got? Are you looking to replace anything with a better version? 20 quid would get you a Lowe Alpine Mountain Hat, or a silly hat as my missus calls it. It may look silly, but it is waterproof and warm, and you can get it in various colours and sizes. One of the best winter hats I ever bought!
Or you could get a Vostok watch, keeps good time and are nigh on indestructible! Good for bushcrafting.