You cannot
sort by estimated value but you can add your own estimated values to each coin.
I posted an answer on how to turn "Swap" on for each banknote
here. So you want to do this with your "My coins." & you would check either what you paid or what you paid/plus any BV adjustments you may have (if you purchased a long time ago). [I use my eBay records or spreadsheet on one window and have Numista open on another]:
Then select "My Coins"
And the coins in your collection:

Select the blue text [COINS] you wish to revise & use the Edit icon (Pen symbol) next to the garbage pail,

A dropdown dialogue box such as the one here should pop up to Edit your Collection.
I have added a "35" to demonstrate & then hit SAVE. [You may have to go back to your "Account Settings" to change the default "Buying Value" to Euro, USD, GBP or whatever currency you desire]
After you start entering estimated values of each coin you will get more interesting summaries on your dash board.
Hope that helps!