Homebrew PCBs

Dylan Smith wrote:
 >
 > On Sat, 24 Nov 2007, Dave wrote:
 >
 > > Is tinning necessary? What is the most cost effective way to buy the
 > > tinning solution and how is it applied? I usually buy bulk if things
 > > don't have shelf life to worry about.
 >
 > I tin my boards because they look nicer, in the main! (The copper
 > tarnishes rather fast).
 >
 > The tinning crystals last a longn time, but made up solution breaks down
 > after a few months - so make it up in small amounts.

Where is the best place to buy the tinning crystals?
Thanks,
Dave