How to assign extracted value to price for monitoring

[debsidian]

My primary use case is to monitor prices on amazon to see if/when I should purchase them. I do this by using a simple xpath filter to reliably extract the price of each item I am monitoring. Price is extracted as nnnn.nn. Right now, I accomplish this by selecting the Webpage Text/HTML, JSON and PDF changes and just monitor the delta between extracted output.

It would be really nice if there was a way to assign the extracted value to the price variable within changedetection so the built-in logic could track price changes over time for these items. ... not just for amazon.com but for other websites as well.

Was wondering if it is possible and if so, how can I accomplish this?