Quoted from smassa:No its not illegal. ....."Price fixing is permitted in some markets but not others; where allowed, it is often known as resale price maintenance or retail price maintenance."
Thats a direct quote from Wiki on the matter. I really doubt the pinball industry falls under the area of concern for congress on the matter.
Wow, wikipedia is your source. It must be right. My source is the Sherman Act and the 2007 US Supreme Court Decision in Leegin Creative Leather Products. If you want a wikipedia article to read, at least read this one: http://en.wikipedia.org/wiki/Resale_price_maintenance
I will concede that it is not ALWAYS illegal, however even legal scholars are not sure where you are and aren't allowed to do it now. So my point is still valid. Most companies, do not blatantly set a minimum price, they use other methods.