I would imagine that it costs a lot more than a normal sales procedure. Unless one has seen an actual bill based on this it would be very hard to know. It probably is hidden in the procedure whereby the sales prices deducts mortgage, mortgage arrears, costs of courts for repossession, cost of bailiffs, interest on interest for arrears, repossession solicitor, sale solicitor, auctioneer, agents etc etc.
I have a sibling in this process, disputing all the way, but it seemed to me there was so many costs, rent receivers etc that on a property in massive NE with arrears that the only person going to make money out of the whole thing was most certainly not the bank. Probably in Dublin with expensive property it's different.