i reiterate what has been said. main maintenance issue:
*cambelt/belt tensioner: imperative these are changed on schedule; if ANY doubt about prior service history, you would be a fool not to arrange changing immediately, so budget for it
*water pump: original uses a plastic impeller, well known to crack over time; needs belt 'off' to change it, so you can change it when the belt is due, using a metal impeller version from a GTV V6
*standard diff: more a preventative measure, as well as performance upgrade; peace of mind, and improved power-down with reduced torque steer; budget for Q2 version ASAP
original suspension isn't great cos it's a bit 'crashy' over bumpers. but it's not terrible. however, during the lifetime of ownership, you will probably want to upgrade with better dampers (and springs).
at 21 years of age - ANY age really - you will definitely want to have a secure, well-paid job, if you want to own and run a V6 GT with 'no expense spared'.
but it's been a fantastic car for me. alfa are yet to release another affordable model that i want to upgrade to.