There’s a Colin Dipper anglo in the coming G&H auction on 10th December 2021: "
Lot no. 1534: “Fine Anglo concertina by and labelled Colin Dipper, no. 103, with thirty-four metal buttons on pierced foliate metal ends, with seven-fold bellows and electric pickup, within a green canvas and tapestry case”
https://www.musicalinstrument-auctions.co.uk/sale/4/1534/Fine-Anglo-concertina-by-and-labelled-Colin-Dipper-no-103-with-thirtyfour-metal-buttons-on-pierced-foliate-metal-ends-with-sevenfold-bellows-and-electric-pickup-within-a-green-canvas-and-tapestry-case
There is a thread on this on concertina.net : here
Looks like it will be expensive then. On Reverb a Dipper went for 4,648 euros a while back.
https://reverb.com/item/30302902-colin-dipper-county-clare-concertina-11a
Another Dipper 3 row anglo, made in 1982, in the coming G&H auction on June 17th, 2022 lot no 1561.
“Fine modern English three row Anglo concertina by and labelled Colin Dipper, West End House, Heytesbury, Wiltshire, no. 51, in G/D pitch, with thirty-five buttons on pierced nickel ends, seven-fold bellows and gilt tooled sides, leather case”
https://auctions.gardinerhoulgate.co.uk/catalogue/lot/1688bc46184fa26e88b8ca1f8765589a/63b778f7668dabe928d3800924a99077/musical-instruments-lot-1561/
Sold for £4000 + fees and tax.