I'd recommend you have a chat with Richard Grace - he will give you a balanced view of the 3200 and any of the Maserati Range.
Personally, I don't think the 3200 is ever going to be an appreciating classic (except perhaps an Asseto Corsa). Some parts are getting scarce to get hold of and some might not even be available new (so sourcing from a scrap car is the only option or pattern manufacturer). The 4200 Coupe and the GranSport have a much better record on reliability ad maintenance costs - but if you get a bad one of either of these, it can end up costing you big money. If its a 3200 you have your eyes set on, Richard is likely to be able to source you a good well sorted car that has been through an independent inspection. If you don't know much about these cars, I'd resist the temptation to buy privately without any warranty (though yes, a warranty on such an age of car has many wear 'n' tear clauses that wont pay for repairs), but if you do, make sure you have a independent inspection (around £300) with a full report.