Shipping via ocean is becoming very expensive, due to carriers "parking" vessels, a general drop in space of 27-ish%. Believe it or not, the vessels, both import and export, are over booked at this time. Carriers creating a space shortage and then raising rates.
As a top of the head guess-timate I would say appx 6 to 8,000.00 just for the Ocean Freight. Upon arrival in Spain you would have to pay duty and a Vat of 17% of the landed cost.
Also, US Customs requires that you be the legal owner of the unit.
If you are still interested PM me.