In the last 15 years I've searched for antique mechanical machines in Reno, Sparks, and LV and couldn't find any. Many (most?) of the antiques have payback probabilities that are lower than the permissable limit in Nevada. The machines at McCarran airport are modern reproductions, and the genuine machines at the Golden Gate in downtown LV are in rough shape and not for play (I seriously doubt if they work).
However, there still might be some Bally electro-mechanicals around in off the wall places because they offer higher jackpots and usually meet the minimum paybacks, as well as being fairly reliable and having lots of spare parts available.
Marshall Fey, the grandson of Charles Fey, the inventor of the first 3-reel slot, the Liberty Bell, had, until early last year, the Liberty Belle Saloon in Reno, and an enormous collection of antique slots on display, including a genuine Liberty Bell (valued at $80,000 to $100,000+). Too bad it was torn down for a parking lot.

Here are some of my slots, all in perfect working condition, for your enjoyment:

1931 5c Mills War Eagle w/1950's hand carved stand

1940's 5c Mills Vest Pocket

1960's 10c BDR Prototype

1930's 5c Mills Brown Front

1933 1c Pace Bantam & 1928 25c Pace Bantam