I know that in New Hyde Park there's a place that deals in arcade machines... A friend lives near the corner of Jericho Turnpike and 12th (Street? Avenue?) and we took a short walk from there to check the place out, but it was closed. I could find the exact address, if you'd like. Email me at jstookey@yahoo.com if you're interested. While window shopping, it looked like they had a bunch of really nice cabinets in there (which says to me they're probably expensive), but maybe they also have some machines that aren't showcased, like cocktail cabinets. Who knows?
I would also suggest building your own. Preserve the real machines that are out there. It probably wouldn't be too terribly tough to put some planks together to make a wooden box that would house a better machine than some little pacman cocktail cabinet.