I always laugh when people ask "how did you get so many of _____?"
Umm... I bought / traded for them. How else does one acquire Lego??
(If you don't know about Bricklink, you need to get familiar with it. It is a great resource once you get to the point where you need specific parts or large quantities of something.)
Also, if you want good pictures, one of those little tripods can really help a lot too. My iPhone 4GS actually takes better pictures than my 12 megapixel camera, half the time. I think photographing Lego is one of the trickier parts of being a good MOC'er. It takes a lot of resources to take good pictures, often beyond what most TFOLs can afford on a tight budget. (lightbox, lighting, camera, tripod)
Lastly, plan on spending some time in a photo editing program. Most of the "top tier" guys never post anything without spending some time cropping, adjusting, and tweaking in a photoshop-type program (I use GIMP - it's free!) to get their pictures to turn out just right.