Of course full time kirtani should be paid a living wage.
This has always been the case, Rababi tradition which was only abolished by SGPC, existed form the time of Guru Nanak Dev Ji, these were full time Muslim kirtani who's sole life purpose it was to sing Sat-Guru's bachan.
You don't need to look further than the one of the last true great kirtanis who did over 70 years worth of nishkaam seva at Darbaar Sahib - Adhan Shaahi Mahapursh Baba Shaam Singh Ji Seva Panthi.
Their life was dedicated to performing the most beautiful kirtan in Sat-Guru's hazuri keeping full kirtan maryada including using Guru Arjun Dev Ji's gifted Saranda.
Whatever living wage is agreed, the key is that you do the kirtan for your Guru (and as per Guru's hukum) and therefore always in shardaa, nimrata and prem.
No difference to Gyaani's who look after the Gurdwarai, it's a full time seva, and you and they live in grihisht, so have to feed your family.
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