If you've got $20k to put down, I think buying new would be a pretty safe idea. You wouldn't really be saving all that much when buying used, and you wouldn't run the risk of inheriting someone else's problems.
And like @
calidus mentioned, Subaru's got some very good financing deals - I thought that USAA was giving me a fantastic rate, but the dealership easily beat that for me.
FWIW, I put about 15% down on mine.