Look on ebay for a second hand fork like a Marzocchi, Rockshox, Manitou, ect.

Something like these:

http://cgi.ebay.co.uk/Marzocchi-Bomb...item3cb81d4b8f
http://cgi.ebay.co.uk/Marzocchi-Bomb...item3f0a0eb23d
http://cgi.ebay.co.uk/Marzocchi-44-T...item35b22db841
http://cgi.ebay.co.uk/Rockshox-Pike-...item3a6645eadc
http://cgi.ebay.co.uk/Rockshox-Pike-...item2310f13014
http://cgi.ebay.co.uk/Manitou-Sherma...item45fabff634

More here: http://sports.shop.ebay.co.uk/Bike-P...4.l1513&_pgn=1

* If you buy a second hand fork make sure the steering tube is long enough.
* You might need a new front wheel too if these forks use a different axle to what your current wheel uses.