Definitely used or new/old year model is your best bet…….by far. Hard tail is good for trails, but not for Down hill. Look on Craig’s List, E-bay, or go to a shop and ask if they have old models still around. A lot of people buy great bikes, and never use them.
I found a used $3,000 BMC Speed Fox on Craig’s List for $900.00, and a $6,000 Cannondale Jekyll for $2,000. The Jekyll or Trigger are great because you can change the suspension and geometry with one button. I found the Jekyll on E-bay from a deal in New York City that was brand new but 2 years old. Many dealer have to stock all the models, but in certain locations they don’t sale. The BMC owner broke his collar bone after 3 rides, and never road it again.
For down hill you need a slacker bike with 140-160 inch of travel that can take the beating. Good to have a chain guide as well.
I hope it helps.