What this shows only 5 titles from the graph, but should illustrate a few points of what we are discussing about sense-making with ILL and acquisitions.
For the titles "A pilgrimage to Kashi" and "Contemporary Indian writings" the cost to purchase and borrow are close enough to purchase, but more importantly, the # of libraries in Worldcat that hold the title are below 10. Acquiring these titles would diversify the collection and meet our user's needs - irrespective of various other selection factors; publisher, LC#, etc.
For the title "Blood and honour" the economic reason is simple, $5.99 to buy, or $25 to borrow - no brainer - twice. Actually, it's $5.97 new and $0.01 used depending on the edition. So, this one is a worth purchasing, but may or may not be worth collecting. The Library can decide, if shelf space is more important than this popular (Amazon reviews are very high for this title), than the Library decides either to give it to the user (and save lots of money over borrowing it - treating it like a copy), or to discard it to Better World Book, B-Logistics, etc. and maybe get some money back from re-selling the title.
"Confederate Catholics at war" may be an opportunity to acquire if it's in the LC# range we want to grow in, and an opportunity that is supported by 2 of our researchers, however, this one depends on collection building profiles - which ideally are machine readable.
Lastly there is "Classic garden structures", which just for the cost is worth buying, and because I love gardening (hate weeding though), I think we should acquire it and shared it with the three people who requested it.
Hope this chart and this helps illustrate some of the factors worth exploring as new workflow and user interface design of the Get It System. Appreciate hearing your suggestions as well - please post a comment; thanks.