6ft 2 inches is good enough for vader. You can make up the difference with lifts. Chris Greene is our Vader in the Golden Gate Garrison and he is 6ft 3 inches I believe out of costume. In costume he is 6ft 7inches. The costume cost can vary wildly depending on the quality of parts you get. Anywhere from 2k for budget vader up to 5k+ for all premium parts from the best vendors. It is an expensive road and the wait for parts can be agonizing from what I hear but worth it. Rubies is tempting because it is there and cheap but as they say you get what you pay for. There is also Anovos but I don't think they are accepting new orders at this time so your best bet is to look into existing vendors.