I believe they're owned by United Franchise Group, same owners of chains like Signarama and EmbroiderMe.
They aren't Apple authorised, so they have more flexibility over repairing with second hand or aftermarket components. Components would most likely be imported from China, but non-official components as Apple doesn't sell those outside of their own service provider network.
Second Hand repaired machines and Mac / iOS repair seems to be their main business. They also purchase machines as trade-in for a reduced price and sell them for a profit, somewhat like the pawnbroker model but dealing exclusively in Apple products.
Haven't purchased from them personally, considered looking at some of their older model iMacs and Mac minis but their prices - at least on their website - seem to be a reasonable amount above private resale value. You would receive an Experimac warranty on the machine, making it eligible for in-warranty after-sales service and support through Experimac stores, but to me as someone that does my own servicing and repairs that wasn't enough to justify the higher price.