take a look at Rose - the Unchained http://www.rosebikes.co.uk/products/bikes/mtb/enduro--downhill/the-unchained/
I think that's the cheapest 'full bike' for DH that you can buy new - at £1814 but you might find it difficult to source in your country (cant see a flag on your profile)
if you're looking to buy used, commencal supremes normally come up pretty cheap and they're race proven frames