A downside of building a Mutant cube is that, because the focus is so heavy on Evolutions, it is difficult to include the high HP, high damage EX cards of the current format
Clockwork Knight Link-1 monsters have historically always been used for broken combos, and Clockwork Knight fills this niche perfectly by being an easy-to-make Earth Machine monster
As for negotiating itself, go watch a few episodes of Pawn Stars
The first are cases where the bug gets pressed into the sheet prior to printing, resulting in a flattened bug thats covered in ink
Because scarcity was largely the driving factor behind skyrocketing TCG prices in the past, the higher population of cards means a potential drop in card values
This card is difficult to find in perfect shape, so the market price is a TCGplayer estimate based on a handful of sales, with LP copies maxing out at $69.99, giving some reasonable credibility to the $94.50 market price