any bookseller I guess in Liverpool or even in Douglas or even further afield (eg look in the Manx directories of the period on www,manxnotebook.com (Liverpool had similar directories from the 1760s) - many smaller printers would also have an associated shop but booksellers had been in business for 3 centuries or so by time of publication of that book - these small books often on religious or moral themes were common to use as gifts or keepsakes