This might be of interest also. Easy to compare grades with the retail cost
https://docs.google.com/document/pub?id=1OTND2bQH0vhlbCf7c2sN8H1vzmT7xagUSXhewGB03SE

Dr Bob: I'd like to add your schematic to the document, with an attribution of course.

It should be noted that the Smith - Parker comparisons in Houchins represent catalog MSRP; not the usual purchase price