This is what Hagerty currently lists for the '84 model year: https://www.hagerty.com/apps/valuationtools/1984-Ferrari-400i?id=116931
That seems a bit low considering what we can observe lately... This side of the ocean, things are different. Here what is listed in France by a famous magazine Cote : FERRARI 400 |LVA-AUTO : argus voiture de collection Prices are for cars in "good condition"
The Hegarty guide prices are way below the prices here in the UK. The cheapest 400 in poor condition but still driveable would be about USD 30k here. You'd need to spend USD 50k for a decent car, and more like USD 70k for a good car from a reputable Ferrari dealer. A concours version would be at least USD 80, and for a manual 365 in best condition you would well in to 6 figures. But it's not unusual to see these cheaper in the USA than is the case in either the UK or mainland Europe. I've not used mine for a month, but visiting the forum today has inspired me to get it out of the garage and use it for the trip to work this morning. Hope it stays sunny today!
