Those prices don't seem to be out of line. The market is flooded with male spiders, pastels, and yellowbellies... You'll be surprised at what you can get for a really good price if you meet up and offer cash.
You're mistaking the prices. $500 is for his black pastel line that can make those Black Razors (when combined with an Ian G. line black pastel). If you want a Black Razor, he's charging $6000 for those.