It is legal
You can sell a car without a current Warrant of Fitness. The buyer just cannot drive it on the road until it passes.
Who buys them
Wreckers and parts recyclers buy unwarranted cars every day and tow them away.
What it is worth
Price depends on weight, parts demand and condition. Many land between $150 and $1,500.
Read more: failed WOF options, or get a quote.