If you want something to grow with and that will give you a lot of fun, get a Laser. You may be able to get into a late '80s model for $1,500. I've never heard of a Barnett but the set up in the pics looks pretty lightweight - I'd say a Laser is a much better piece of equipment. If the Laser seems too intimidating, then get a Sunfish. Try eBay and local for sale books, also www.laserforum.org
There are plenty of How-to books around for Laser sailing and racing.