William,

Ok, here's what I could suss out about Ken Evans. in the late 80's he was the builder
of the Australian Olympic track and road frames. Worked with 753 Reynolds steel and
his prices were lower than similiar well know European builders.
So, is it worth $500? depends on a few things.
Historically if the bike was ridden by anyone "famous", or won any
olympic or other big name races yes its worth it.
From a non collectors standpoint you are getting an excellent frame
of questionable usefullness (as Crawdaddy said, are you gonna ride TimeTrials?).
One thing you might want to consider is that I've seen a few TT frames lately
on e-bay all brazed by the big name European makers and they sold for less than
this guys opening price of $500.
I got most of the info on Ken Evans by doing search on Google. I really had never
heard of him before.

Marty