where to buy fork springs?

[Nevada Sixx]

my bike rides rough and has a "clank" sound when i land, so i must need new fork springs. where do you buy new springs that are stiffer than stock. is it easy to install them? Just take off cap at top of tube and pull out old and drop in new?
89yz125, 180 pound rider.
thanks.

 

[marcusgunby]

It doesnt mean you need springs-but you need to get it looked at IMO.