You're looking at a budget of 60k+ if you'll be going for semi-pro models like the Nikon D300s and/or Canon 7D.
I think you should get a Nikon D90; hindi mo siya matatawag na entry-level talaga, since it's a really good first DSLR. I doubt mabibitin ka sa features nya for quite sometime. I don't know kung magkano ang price nun used, though. Definitely way cheaper than the D300s or 7D.