stiffer kdx fork springs

[motofox2006]

Hey guys just wondering if anyone can tell me what stiffer fork springs I can stick in my kdx (xr springs). That will be cheaper than kdx springs. Ive priced kdx springs at $180 New Zealand dollars ($90 US) this is a bit pricey for me.

My bike is a 1991 KDX200

And I weigh 146Lbs

Thanx Guys