Here is one path:
Start off with a Weber Kettle. The 22.5" OTS is $89.99 at Lowes or Home Depot. Learn how to set up for indirect cooking and you've got a start in BBQ.
Next get a Weber Smokey Mountain, or if you're even slightly mechanically inclined, build a UDS. You'll then be grilling on the Kettle and smoking on the WSM or drum.
From there you should be totally hooked and there's no turning back.
You might want a Big Green Egg for versatility, and so you can cook comfortably all winter.
Or a nice upright cabinet style smoker for more capacity so you can show off your skills to more people.
Eventually you'll want a big offset stick burner, just because it's cool and sexy.
Mister Bob, Pitmaster - Bob's Hogs. KCBS CBJ #31759 - IMBAS Certified MOINK Baller