The feature is already provided on eBay, Robert.

After you have specified your search parameters and get the first page of lots that meet your screen, look at the right side of the page, below the line that gives "eBay Time". You will see a link that offers to "Filter by Price Range". Click and you'll get another page to specify min-max prices to be added to your search criteria. There doesn't seem to be a way to build this into your original search... you have to do this 2-step each time, but it does eliminate looking at all the cheap limited edition chips that seem to comprise much of the casino listings these days.

It also eliminates many of the inexpensive antique poker chips I look for, so I don't use it, but it's there for those who can benefit.