The SD9VE is a pretty good inexpensive starter gun. Keep in mind that the gun has no thrills. Its a very basic gun but its a gun that will be very reliable. For $399.99 that saves you some money for ammo, lockable gun case, and trigger lock because you will need all that. Sometimes stores put them on sale for 349.99. Save yourself an extra $56 with the tax difference. That will buy you an extra mag. If you pick everything up on a sale day it will get you a bunch of extra stuff on that $600 budget and I know lots of people with out licenses that purchase a restricted firearm on a sale day and the store just holds it until you get your restricted and they can transfer it to you. Yea the SD9VE's trigger is heavy. 8lbs. But if you can master that trigger dude you can shoot anything.
Used guns on the EE are always great. You can get a very good quality, lightly used gun, for your price range easily. Glock, M&P, CZ 75.