I suggested several years ago that selling a complete set on CD-ROM for say £20-30 would actually give them a better return than selling paper - the cost of paper + duplication + postage (esp international) is high and increasing very quickly - little money is actually made and that relies on donation of considerable free time by volunteers - CD's are cheap, easily duplicated and could readily be made available via Manx Museum etc.
However I said the same re Brian's census indices - I suspect that in both cases people feel that easily copyable CD's would close off future sales.