The cheapest 2 manuals are arrangers with additional keyboards and pedals added like TRX System https://www.musicland.co.uk/shop/trx-organ-systems-1/ full 2 manual organs start from around £8500 https://www.allensmusiccentre.co.uk/organs/ringway/rs800.html most organs that are purchased are in the £10,000 to 20,000 range, with the main ones being Bohm https://www.keyswerk.de/index.php?a=instrumente and Wersi http://www.wersi.net/ the cheapest 3 manual is probably the Bohm SE60 which costs from around £18,500.

There are also plenty of used models available from various manufactures.

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