Pets Mart are usually located in huge shopping mall: in the vicinity of Washington D.C. - Alexandria, Greenbelt, Oxon Hill, silver Spring and Kensington.
I went to Alexandria but unpopular pet like crayfish was by no means on sale.

Totally fish is located in Layhill Shopping Center, 12 miles north of the downtown Washington D.C. As the ad. says "metro area's largest selection of freshwater and saltwater fish", a variety of fish are displayed but Totally Fish is still smaller than Pau Pau Aqua Garden in Tokyo.
When I went there, there was a tank for Electric Blue Crayfish but it was empty.
There was also another tank with a tag of "crayfish", where a couple of brown crayfish are kept at a price of $2 each. They are likely to be local crayfish, but I know neither their common name or scientific name. Anyway they are sold not for feed for large carnivorous fish but for pets. What lucky crayfish they are, while many red swamp crayfish are poor to be sold for feed for large carnivorous fish in Tokyo. When I went to Totally Fish a couple of days later, the tank was empty.

The United States is vast! Driving long way to purchase crayfish but eventually finding they are sold out! - That's why on-line shopping is popular.
Some on-line shops are dealing in Electric Blue Crayfish, for example, Aquarium Fish at $18 each, Fish U2at$20.83 each and Nautilus Aquarium Shop at $11 each.
Sandfire Dragon Ranch deals with the most wide selection of crayfish - 9 crayfish such as Destructor (Yabby), Red Claw, Night Stalker (Marron), Tiger Lobster, and Orange Flame Lobster.
Besides, Bob in New York has got the domain name of Bluecrayfish.com and personally sells blue phase of N.Y. crayfish.