Again, Welcome to the forums--- careful-- you will start playing hookie from work and lying to friends (about why you can't hang out) in order to satisfy the urge to throw a fly line.....
That being said-- as seems to be the consensus-- $4/500.00 is plenty to get started (even 'stay started') and should cover about about everything you could/ would possibly need if you are 'thrifty'. (will it cover all you would/could want? not likely...)
As jbb stated-- If I had to chose one rod for all of eternity, it'd definitely be a 9' 5 wt. (generally speaking the most 'versatile' length and weight of rig)
Sounds to me like it is time to hit your local fly shop.....