Err um well I guess that's my professional streak showing. I was (long ago before computers) a librarian. We can't afford to buy 'book and non-book materials' for a library and find it wasn't suitable, so we research the item first. :oops: I am not an impulsive buyer of anything.
However I also worked in the film & tv industry where you learn to think in millions, so real life can be a challenge.
At this point I am trying to develop an 'eye' for glass, a visual vocabulary. It is difficult to judge 'quality' or even colour, from a book or fuzzy pic on ebay. I don't know how much UK & European glass would have come here, and therefore what can be reasonably expected to surface for sale.
I am moving increasingly to buying Australian art glass from the start of the studio movement here, because I can see it in person, it is more likely to have provenance, and may have a cultural relevance lacking in the nice stuff I see online.