Many local authorities and county councils produce their own BaR registers. These vary in detail ranging from full colour documents with illustrations to simple lists or tables. These registers will usually contain buildings where work is underway and buildings where there is no possibility of reuse along with those which are in need of news owners or new uses. All are helpful and they form the basis of the SAVE register.
English Heritage produces a register of all Grade I and II* listed BaR in England, and a comprehensive register of BaR in London. It includes occupied buildings and buildings under repair. You can get a free copy of the register or London volume from English Heritage or view the entire register on the internet
The Society for the Protection of Ancient Buildings produces a quarterly leaflet of listed buildings for sale which is available to members only. For more details contact SPAB.
The Ulster Architectural Heritage Society produces an annual catalogue of buildings at risk in Northern Ireland. The catalogue is free, but you will have to pay for p&p unless you collect it in person.
The Scottish Civic Trust has an excellent register of buildings at risk in Scotland. The annual bulletin and individually tailored printouts cost £5.
Don't forget to check small local estate agents. Quite often people underestimate the interest there is in buildings which need repair and consequently they are only marketed locally. You should also read the local papers to see if any buildings come up at auction.