@HikingStick

It already splits cards into separate rows for different Sets, Conditions, Languages, Foil, etc. What's adding another field that does this? This would be an optional field, so you wouldn't need to enter it for trades, cards where you just don't know, etc. It would mainly be for tracking the price paid for items you do know. I think it'd be useful, and shouldn't be too difficult, and not require much more storage. I currently need to keep a separate spreadsheet for this that would no longer be required if Deckbox had this data.

I would like to see a field where I could enter the price I paid for a card.

I see this as being useful for a few reasons:
1. Cards are an investment. Nobody wants to buy high and sell low.
2. It will be easy to see when one of your cards skyrockets in value (consider selling) or plummets (consider buying).
3. When trading, I prefer to take into account the amount I paid even though the value has gone up. That way, I can think of it more like "would I pay x for this new card?"