MrD, the only one I know of in 1/48 is made by Dragon/DML, but it can be pricey if you find one, as they're quite rare. Roden makes one in 1/32 scale (a fairly complex kit) and Revell does a 1/28 scale version, which is simpler.
I also know of an all red Albatros D.III that was flown by Godwin Brumowski. Eduard makes a few kits of the D.III, but I'm not sure if they include markings for that bird. I'll check that out for you, and also see if there are aftermarket decals available for it and post what I find.
edit - OK, Eduard kit #8017 is the Albatros D.III 'Early Version' and has markings for an all red mount flown by Richthofen. They pop up on eBay from time to time. Also, Flight Decs has a sheet (#FCM4816) that has markings for Brumowski's mount.