Vandersteen 2ce + 2 vandersteen subs better than the Sig 3a? Or the improved midrange and depth in the sig 3as are worth the money alone. Or should I just go for the sig 3a and upgrade to the subs later on in life?
I could afford to buy the vandersteen 2ce new but would have to buy the sig 3a used. Is there any disadvantage to buying these vandersteens for 30 to 50% less used v/s getting them new at the dealer? I notice a big price gap between new and used ones out there.
also there is a lot of ...
Before you do anything else you really need to go listen to some speakers. If you can get an in-home demo that would be fantasitic, because you space and gear will have a big influence. Also keep in mind that whiel a lot of us are fans of the Vandys, you might not like them at all. It maybe that the Thiels, VMPS, Paradigm Signatures or some other brand sounds better to you than Vandersteens.
WRT the Vandys, what are your priorities? I don't mean how much you listen to music versus how often you watch movies, I mean which is more important to you. If music, especially 2 channel music, is your top priority, I would suggest the 3A's. If movies are #1 for you, go for the 2Ce Signatures and the subs. Of course, if you can get the 3A Sigs now and the subs later...
I think buying used is a good thing, as long as you are careful about it. Much of my system was purchased used, including my 2C's. The best bet, especially when buying used speakers, is to try to find someone reasonably local and see if they will demo it for you in their system. Don't expect to be able to demo them in you own system, unless you already know the seller. Also keep in mind that used gear is always sold "as is" or at best, with a warranty against being DOA.
Unfortunately, I know personally that speakers, especially large floorstanders, are easily damaged in shipment and getting the shipping company to pay for the repairs can be a nightmare!

Keep in mind that the seller is under no obligation to take them back or refund your money if the damage was caused by the shipping company.