Good Source For Note Values

Ha.com has a pretty good historical record of sold notes. You just have to be a registered user to access the data. Registration is free.

Currency books like Paper Money of The United States 22nd edition can give valuable info for a collector on currency values and which to look for, but its around $45 new for a print softcover version and less for a ebook version. https://www.coin-currency.com/page8.html There is also a cheaper version like A Guide Book of United States Paper Money 7th Edition that have less grade values such as only circulated and uncirculated vs many different sub grades and no colonial currency that may also be ok for beginners.

Otherwise you get into specialty books or as mentioned you can use sold listings from auction sites and ebay sold listings to gauge current selling values as a secondary avenue for research.

Thanks for all the suggestions. Very much appreciated. I have an account at HA.com so I will use that more often to check comparable pricing.

All good advice.
Personally, I use the guidebooks for the written tidbits of information usually not found anywhere else and use recent data on similar SOLD items for pricing.

Yes it is a good resource, the online or software can get just the types you collect like small size, large size, or even nationals, colonials, or fractionals. I'm sure dealers and those who regularly buy and sell would find it something worth trying (there is a free trial). You could potentially spot price trends on currency by keeping that much up to date. It also allows you to confidently price your purchases for sale where that cost might be more worthwhile. Thanks hfjacinto for mentioning.
http://trackandprice.com/us-currency-purchase/

I can imagine that those who deal less may find the $45 print book (or ebook) along with just looking things up at heritage, ebay, great collections and others to be enough. I guess coinfrog finds he can do without the guide and just look up pricing as needed, but personally I find the book to be invaluable to see notes not currently for sale, info on the notes, relative differences among values at a glance etc. It also has some things like star notes that some of us might be interested in and was very happy I purchased that book. If I started selling currency regularly on the ebay store perhaps I'd test the software mentioned above from hfjacinto.

Cool. This is by far the best book in the market so I'm sure you will get a lot of benefit from it. There are very few books that are absolute necessities for US Paper money collecting, but this is one I would say whether beginner or more pro. I do understand as others mentioned that pricing in a print guide can go out of date, but you know where you can potentially get more up to date pricing as needed both for free, or for a fee if you need the most accurate up to date info once you understand the basic info and general pricing. Feel free to post what you like about it later.

Yes they said Look for a new edition in 2024 at least (for print). ebay had one print for 50.45 https://www.ebay.com/itm/364626698825

However you can still grab a digital copy if you want for 29.95 for kindle if others have it too expensive.
https://www.amazon.com/Paper-Money-.../B09G8G6ZGC/

They seem to still have electronic ebook version for 29.95, and seems a usb pc version you can ask about. Might be better anyway if new version with updated pricing is coming within the year in print and you don't wish to wait.

https://www.ebookshop.coin-currency...ion/p/169892
https://www.coin-currency.com/page8.html

On a side note I see they also have electronic version (not print) of Paper Money Errors which I have in print but also very hard to get in print without higher pricing usually until a new one comes out
https://www.ebookshop.coin-currency...rors/p/79802