Spyder. Spefically the Xtra. Best semi-auto for it's price IMO. Very easily upgradable :beer:
Your beginning "marker" should be the one you play around and tinker with. Then you move onto the better stuff, maybe even Electronic Markers
NOTE
Do NOT, I repeat, NOT, get a marker unless you're going to a field VERY often. My rule of thumb for beginners is to go a few times using rental equipment, and if you're absolutely sure you will be somewhat dedicated to this, then get a marker.
And the first piece of equipment you should be getting is a good goggle.