Well....not collecting inlay chips would severely constrain my focus on obsolete Las Vegas chips. It's always smart to be somewhat cautious when buying a rare (ie. expensive) chip. Buying from a reputable dealer is a big help as he (or she) has a reputation to defend and as a member of our Club there's the code of ethics. Most inlays are made of a material (linen?) that is then pressed into a mold producing a uniform cross-hatching across the clay and the inlay. Here's a close-up of the Circus Circus 100 prize unit recently sold by Spinetti's for over $1500. Notice the exact alignment of the inlay and the clay cross-hatching. I would think that's very hard to duplicate. In my more that 25 years of collecting I only recall seeing one other example of this chip. Given the mint condition of the chip my concern would be that a quantity of this chip has been found. If I'm going to bid on an expensive chip I make it a practice to ask the seller if he's aware of more of this chip having been found. Most seller respond directly but I've also gotten responses like "I just have the one for sale" or "I don't know exactly how many of this chip there are."
My two cents