IMO:
If you have a spreadsheet with prices the prices should be only the price you paid for it. So you can keep track of what you have put into the collection. The price you enter will change. It is not the same as a year ago or next year. So why do it?
As far as people helping you out with a spreadsheet it may be hard. If I had one it may not be set up like yours. So you are asking members to update your spreadsheet and hoping their input is correct. If you just want the data and you will input, it Why not just use this site as it is about 99% of them
I started my excel files for my Husker collection about 20 years ago. If I started it today, I would do things differently. The work to change everything is too much at this point of time. Only reason I'm not just using this site is: I have approx. 300 cards that are not supported here.