I've purchased all of my meers, seven in all, in person at various dealers. Each was in pristine condition, snowy white and the colors, and depth of such, they variously exhibit is the result of my smoking and caring for them.
Just an observation and I am sorry I can't be of help in securing used meerschaums. I might suggest yard sales and the like. Possibly pipe stores which deal in used and antiques. And, of course the ubiquitous eBay and the like.