You are not going to get something good for $300, so prepare to compromise. Our local Costco has some lower end Aluminum Manfroto tripods with head for around $200. I don't see them online, and I only looked at it briefly, since it was not a pro quality unitet, but more of a high end consumer unit. Much better than the junk you find at Walmart.
What you want is a tripod with a under hook. Hang your camera bag or other weight on the hook to stabilize the tripod.