Anne owns Gatcombe outright and has made the estate a profitable business. Part of Edward's Bagshot Park deal is that he can sublease the stable block to others ( I think he worked that out when Ardent was still running), so I'm sure that helps. Charles, of course, had the Duchy of Cornwall funds to use for upkeep.

The late QM let things get into a bad state at both Royal Lodge and Clarence House and both Charles and Andrew had to carry out repairs and refurbishment before they could move in to their respective residences. If Andrew really has let things get that bad at Royal Lodge, then he should let any monies owed him at the termination of his lease go towards the repair work needed. Even if the Royal Lodge is covered by a Sovereign's Grant or the Crown Estate, there will once again be cries of "taxpayers are paying!" and so on and that would be unfair on the Waleses if they move in.