Used TC Grey Hawks in good condition sell for about $175 - $200 because they're stainless steel and not made anymore.
If a NIB Grey Hawk can be found they usually sell for even more.
One would need to be in fairly poor condition or up for sale in a pawn shop where the shaop owner didn't pay much for it to end up selling it for only $100 - $110.
$150 is a pretty fair price depending on its condition.
Congratulations if you can buy it for less.