Overall, I think the idea sounds interesting. I would probably use it and pay a reasonable amount for cataloging my personal collection & traders, though I haven't added my chip collection & traders as yet.
Definitely need a comment field, and room to upload personal pics of chips and/or traders, for those chips that vary from the standard picture. That would be extremely helpful with Trader chip listings (both buy & sell sides), where condition on chips may vary.
As to pricing, maybe a one-time enrollment fee, then an annual subscription fee too, to pay for extra bandwidth & development / maintenance.
As comparison the "Collector's Assistant" software is $79.95 to purchase.
I don't have a copy of Collector's Assistant, but you may want to compare its functions to your concept of a ChipGuide-driven product.
If you can equal the functionality of that program, or come close, then a price like $50 (1-time) plus $20 a year would be attractive.
Perhaps a 90-day trial for free?
Would a revenue-producing product fit with the non-profit status of the MOGH? There are other considerations too, if you move forward with a fee-based product.
Also, I would hope that you would expand & incorporate the Chip Molds project work that the CC>CC Standards Committee is working on ... if it's finished in the near future.