Is it just me, or are the older cards valued much higher on Deckbox? I am not sure why it has Sol Rings from Revised worth nearly $20.

It's an issue with how Deckbox and the TCG Player API work together where the prices are averaged across all versions of a card. So while the Commander version of Sol Ring will go for $6 on average, the Judge Promo and Alpha versions go for over $100, which raises the average price for a Sol Ring quite a bit.

The issue is hopefully being resolved in the next release that will hopefully be coming out soon.