IndustryNet.Com review: Scam letter

I'm an artist, with a small art business, who received a letter today from IndustryNet.Com a "company" that supposedly advertises businesses that provide (and I quote) "machinery, equipment, parts & supplies". They're wanting me to pay them $233 to be featured in their "marketplace". This is obviously a scam. The dipsticks who sent me this letter can't even tell the difference between an art business and an equipment supplier. When I looked them up online this is what I found:
Some businesses have reported that they received an invoice for an advertising service after returning a letter that appeared to be a request for a free listing verification. The company has been described as using this inquiry letter as an order form.