You could use the CWS as a cheeper alternative but I would seek out the Harris ones. The thing that probably would not work out to well is the coverage overlap between the CWS and the Harris as Harris is a roll of the dice as to what they are going to update on each supplement. You might have several years overlap in one country and miss 5 years of another country. I have been able to recently find all of the supplements less the 1985 back to the early 70's on
ebay. Also make sure you have the 1997 supplement and not just pages that go to 1997, that could be the 1998 or 1999 supplement. I keep the supplement cover pages at the front of the first volume just so I and the next owners know what supplements are in the set.