pianists buy the pianos they have at home. The postman gives them a reduction, the one he gives to his resellers, but the pianists pay for their instrument.
I knew Nelson Freire very well who had three Steinway concert cues and a Model B at his home in Rio de Janeiro: all paid for out of his own pocket and the last one delivered from the United States to Brazil, which costs a fortune in freight... The first had been imported from Hamburg during the dictatorship of the Brazilian generals who had passed a special law so that imports would not bear the 100% tax applied to the piano... because a Brazilian brand made a grand piano and wanted to be protected: but what professional would have played an Essenfelder? Nobody... So the generals admitted that Nelson Freire could legitimately demand to work on a large Steinway.
For concert service in Europe, it is rarely Steinway which provides the service and they are professional rental companies, unlike in the United States. But today the popular piano is Steinway, closely followed by Yamaha whose CF III is sublime, then Fazzioli, Bechstein and finally Bösendorfer who has a few but rare fans (including Andras Schiff)...
in Euroe, It is the organizer who pays for the rental of the piano, its adjustment or its transport. Except when the pianist follows his own: which is extremely rare. Michelangeli, Pollini did that. Schiff does. Richter was followed by Yamaha everywhere but paid nothing to Yamaha, a rather unique case. The Japanese were so proud that Sviatoslav Richter loved their piano more than anything...