Air conditioner disconnect boxes can be found on Amazon and at The Home Depot website. Models of both fusible and non-fuse disconnect boxes are available at both online stores, as of 2015.
The Siemens WF2030U Fusible AC Disconnect is available at Amazon for $14.31 plus shipping, while the Siemens WN2060U Non-Fused AC Disconnect sells there for $16.38 plus shipping, as of 2015. Disconnect boxes from other manufacturers with varying specifications are also listed.
The Home Depot advertises the Eaton 60 Amp 120/240-Volt 14,400-Watt Non-Fused Air Conditioning Disconnect for $6.78 plus shipping, as of 2015.
Amazon offers free shipping for orders over $35. The Home Depot offers free shipping for orders over $45, and in-store pickup is free for all of their advertised air conditioner disconnect units.