The US Issued Fighting Load Carrier is a pretty decent vest. Its adjustable, and you can carry a lot of shit. Right now, mine carries 400 rounds for my SAW, 2 Frags, a small GP pouch for nods, and an IFAK(first aid kit) and I still have room for shit. You can get them for pretty cheap, you just need some pouches to throw on there(thats the expensive part).
Now that I've been in a hot AO, carrying a lot of shit isn't so "cool". I don't suggest an armor carrier, since it doesn't offer any real protection, it just makes you more likely to go down as a heat casualty when it gets hot outside. Go as light as possible.