You don't necessarily need to quantify the value for every item in this case, or in some cases for quantifying achievements I'd look for other measurements outs

You don't necessarily need to quantify the value for every item in this case, or in some cases for quantifying achievements I'd look for other measurements outside of a $ impact or estimate of time saved. For example, for something like fixing bugs, if its difficult to peg it to a financial or resource benefit, measure how quickly you closed your issues, point out that all of your fixes had no further issues, etc. If you delivered FeatureX but FeautureX received no traction, use this as a starting point to have a discussion about your expanded role in the company. Perhaps after you've received the promotion/raise you could take a more active role in the design/research phase, and have some ideas available offhand.