The local Saw shops is where you will get your blades. I get my blades re-sharpened for about 6 bucks, and a new one is 8. If you don't have a shop nearby, the nearest city should have one, and making friends with these guys is worth your time. The one for the Ryobi also fits those little 3 pulley band saws. I believe the blade length is 55 1/2" since I made myself memorize this number.
The benefit of the little saw is how thin the blade is. With a little practice get two pieces where a fatter blade on the bigger saw will leave you one.
You want the blade to run against the bearings with a little pressure, and I like a little more spacing between my guides. These bearings should spin freely, and be well lubricated usually with a gun oil, or whats good for sewing machines.
El Destructo you probably don't have enough tension on the blade for starters, and a dull blade wanders badly as well. Another thing I do before starting with a new blade on there is first unplug the bandsaw, then spin the wheels by hand and make sure it tracks perfectly on both wheels, and sits exactly where its supposed to. Band saws normally have an adjustable upper wheel and taking the time to get this figured out matters as well.
On my old 12" Craftsman bandsaw which I moved to Hawaii years ago, and left at a friends place I used wider 1/2" blades and had great results with it. In the future I Manny and I will used it after hunting the hogs down the hill from where it sits..
Rich