What are the safest but also inexpensive (less than 300 dollars) swing sets.

Isn't it funny how things change, when I was a kid, we used tie a rope over a tree and swing from that. We didn't have fancy swings or see saws. Not that our parents weren't as concerned about safety as they are today, it just wasn't a thought.
Pine is one of the softest woods there is. Therefore, swing sets that are made with pine frames aren't the most durable. Another problem with this soft wood is that it tends to deteriorate from the inside out. The wood frame could be rotting away without you knowing it... until the frame collapses, that is!
Pressure-Treated Lumber Can Be a Safe Choice...
as long as the wood hasn't been treated with harmful chemicals such as arsenic or chromium. Arsenic, in particular, has been linked to cancer, according to the EPA. Therefore, to choose the safest swing set for your kids, be sure to ask how the wood is protected before you choose to buy a swing set with a natural frame.
Swing sets that have bolts extending out without being covered with nylon or rubber pose a safety hazard. The bolt ends can scratch, cut and even tear your kids' skin. Choose the safest swing set by inspecting the frame for exposed bolts, jagged corners and sharp edges. If the corners aren't rounded, they should at least be covered with a safe, protective material.
choose the safest swing set for your kids, look for a model that has ground anchors. Ground anchors keep this type of play station firmly attached to the ground. Granted, you can buy these safety accessories separately. But a company that includes them with their swing sets is showing their customers they have your kids' safety in mind. Multiply your swinging fun by four! This built-for-four swing provides a sturdy ride for up to four youngsters. Features:

• Two board swings
• One open station that accommodates a Kettler Gondola, Surfboard or Glider accessory (all sold separately)
• Ground anchors included
• High-carbon steel frame