Nice idea. A couple of small suggestions:
- Perhaps choose some base rate of inflation and determine if the product price has increased in line with that or slower/faster.
- Use a bold font to highlight the product weight.
- Use an archived version of the product page today - that will reduce maintenance time moving forward.
And a question: are you using net or gross weight? When using gross weight it may very well be an update in packaging that is impacting the reported number.