Looking at a few cars as in already caged cars? Unless the car has previously passed a Lemons tech inspection, then walk away. The cage is absolutely something you don't want to skimp on.
Sometimes cages made for other series (Champcar, AER, WRL) will pass muster here, but those cars really don't belong down in the Lemons pit anyways.
You didn't post your location, but there are quality fabricators around the community and around the country that can build a cage for you.
If you want to buy a pre-raced car, the forums here are a good source of candidates that already passed tech.
If you want to build a car from scratch, then just worry about the $500 rule and make sure that the floor pans and frame rails haven't completely rusted to dust.
PS - circle/dirt/derby track cars are almost never good candidates.
1989 Merkur XR4Ti: Project Merkur Space Program - Wins: Class C - Colonel and the Sinkhole 2023 | "Heroic Fix" The Pitt Maneuver 2023 | "Halloween Meets Gasoline" The Pitt Maneuver 2022
1980 Dodge Challenger: Most Extreme eLemonAtion Challenger (Rust Belt Ramble 2021 Dishonorable Mention)