My wife is the librarian for the Cape Cod Choral, as such she needs to acquire music for some works they perform. She buys music, rents music to accomplish filling in the various head counts for different concerts. She also borrows and lends music on a working basis with other Chorales. When she buys music she has a couple of sources she uses, one of which is Sheetmusicplus.com. They do have Henle for piano in Urtext.