JN does have that function though? Once you use your source code to have the checker pull what cards you'll missing, it should then ask you if you'd like to make these missing cards into a wishlist.
Once you do so, you can go to your JN wishlist page and hit "view". It'll then put the JN price of the card under each card. If it's currently inflated, you'll see an inflation notice letting you know.
Lastly, once you scroll all the way to the bottom of the wishlist, it'll give you a rough estimate of how much the cards are in total that you're missing.
Hope this helps a bit.