This is mentioned in the bug list. The current best guess is
that it used to be 500 gold, but somewhere along the way (probably
as a side effect of fixing some other bug), it was accidently
changed to be the current value of 1000. This is a bug, but
is pretty unlikely to be fixed.
-- Please use bron-oly2@bronze.corp.sgi.com for Oly2 correspondence. Use bron@sgi.com only if you require fast response. These statements are my own, not those of Silicon Graphics.