BaseballAmerica.com: Draft: Draft Database
So the Cubs have Almora at #6, slot recommendation is $3.25MM. Currently $276200 under budget, which means if they don't want to pay a tax they can give Almora $3526200. The total pool the Cubs have is $7933900, which means they can spend up to $396695 more without forfeiting a draft pick, but would have to pay MLB a $297521.25 overage tax. Almora can therefore earn up to $3922895 if the Cubs feel like paying the overage tax.
I think Almora signs for $3.5MM because the Cubs are probably going to play hardball and say that he's not worth giving up an extra $700K, and Almora is going to take it and like it.