Mac,
Like 'em or not, the LOWEST sales number commonly cited for global ABBA sales is 150 million units worldwide. That figure is generally used to debunk the 300 plus million plus that's often thrown around, so the real figure is almost certainly higher than 150,000,000. It seems that there is confusion because the record keeping for album sales isn't exactly a precise science, but ABBA appears to be, by all of the counts that I've seen, one of the top dozen selling bands (excluding solo artists) ever. Given that the band released all of 8 albums, it's hard to argue with their commercial success.
If pure pop ear candy ain't your thing, I can see why you'd dismiss them outright. OTOH, some people love that kind of thing and others (including me) find it fun in (very) limited doses. ABBA may or may not suck (depending on your tastes), but they certainly sold a sh*tload of records.
Marty