1) Dont worry about spending too much $$$ on a helmet. Any DOT full face helmet is good. Fit indeed is critical, make sure the helmet feels snug almost a bit too small, it will wear-in nicely. I'd say $200+ is a good range for a helmet. Look into AGV, Shark, Scorpion. Anything above that is definitely better, but for someone on a budget who thinks he might quit, no need to go further than that.
2) Get yourself proper ankle protection. Whatever boots you get, be it motorcycle boots, or just some work boots from Wal-mart, make sure they cover your ankles and feel nice and sturdy.
3) Get some gloves. Road-rash on your hands is a nasty thing. While you can live with road roash about anywher else, having it on your hands will really screw you up and prevent you from being able to work. Any decent leather gloves meant for riding street bikes will do. Just make sure that they have some padding on your knuckles, wrist and forearm. Dont skimp out on gloves. Firstgear, joe rocket, icon and alpinestars all make decent gloves.
4) When it comes to protecting your arms and chest, a proper textile jacket is a a good place to start. If you live in the warmer climates, get a perforated one. Once again Firstgear, Icon, Alpinestars and Joe Rocket make rather good ones.
5) Jeans dont do jack shit. When you fall, they pretty much disintegrate. At the same time, road rash on your legs is something that you can deal with. If you strapped for cash, wear jeans. If you can afford it, buy some cordura pants.
Leathers are king, but obviously cost $$$$.
Here are the links to some online stores that i have dealt with that have excellent pricing:
Motorcycle Helmets and Motorcycle Accessories at Motorcycle Superstore
New Enough Motorcycle Apparel sells motorcycle jackets, pants and suits, boots, gloves, helmets, etc :: New Enough Motorcycle Apparel
Check out cycle gear, they have many outlets across the US and offer decent prices:
Cycle Gear - Motorcycle Apparel, Parts and Accessories
Cheers.