I posted a similar question a couple of months ago. The general
opinion was that these books cost $$$.
Recently, from the online second-hand bookstores I bought the one by
Zoega for GBP 85 and Cleasby's dictionary for US$ 200! Needless to
say it made a big dent in my pocket.
Now www.addall.com lists 2 copies of Zoega's dictionary for around 40
$ each :-(