Apple have give the iMacs a refresh and performance boost:
I've been preparing my wallet for a Mac Mini purchase, but if I do the same Mac Mini spec as the base level 27" iMac (added storage, keyboard and mouse), it comes to £1,837. The iMac would be £1,749.00, nearly £90 less...BUT you also get a dedicated graphics card rather than an onboard one...and a rather lovely built-in 4k 27" monitor.
The new iMacs are also not using the T2 chip, so theoretically wouldn't suffer the reported audio issues.
Just need to work on Mrs Monzo a bit. I've talked her through it but she's not looking happy.