Hiya Neil, You might want to consider a casino that may shut its doors soon. that alwaysmakes the chips popular. You'll have to really pay atttention to casino news but a couple of cndiddates might be the Tropicana and the Riv. Both those places have quite a few obselete chips that would fit in a lot of collections as well as LEs. It would be a good idea to try to acquire higher dinomination chips like $25 or $100 chips as those really become scarce after a place bites the dust. Not many walk as souveniors so higher denoms become scare as years pass. I was lucky enough to snag a $100 Alladdin and am really pleased that this chip has held up so well, C/W gave it R-7 100,125,150...Dang, wish I'd gottten more!
Not a big investment if you work it right. My black chip as a color-up from a $60 balckjack buy-in. Of course, I don't have any special insight as to the viability of the Trop or the pimplous Riv, you'll have to find your own way there, good luck!