Are you handy at all? You may want to consider a gently used bike because you can save a lot.
The all-mountain bike category is getting better for versatility, I ride an AM bike as both an XC or light DH but not for heavy DH. The problem is for a full suspension ride it will be above your price point. If you're OK with a hard tail then there are plenty of good rides in that category. I like RockyMountains (I still ride my old 1993 Fusion as my commuter bike, I've logged several thousand km's on it and it still holds together) but they are expensive.
You should look into a Trek .. man I love my Trek. Nimble, light, and fast and plush enough to taste a little air.
My general recommendation though is that you should pick a bike based on what you're going to do with it. A one-size-fits-all is hard to do well. Jack of all trades = master of none. (This is why I have 4 bikes
People always say "Geez man, how many bikes do you need?" and the answer is "ONE MORE, geez, duh!!!"). My DH bike for example is a Devinci 8flat8, 8" of travel. She does one thing well and that is descend: and she does it REAL well but at the cost of being hopeless for anything but. (I once pushed her down Moosepackers over here which is a downhill run in that you start at the top of a mountain and end at the bottom, but is really a XC trail in that there's a lot of valleys and climbs and plateaus and I can tell you I was ready to barf after an hour of it). That's what pushed me over the edge and I ended up with the Trek - my RM is a paved trail or pathway bike, my Devinci is for places with lift access or truck shuttles, and my Trek is for everything in between. Despite each being a "mountain" bike, the geometries for the 3 are different enough that it's uncomfortable riding any of them outside of their primary purposes.
For that reason you should sort of examine what you think you'll be doing the most, and focus on that kind of riding, and then rent if necessary when venturing outside that category (for example rent the DH bikes when you try DH). If you do the other stuff enough then look at buying a bike for that purpose (and trade up your other if need be, or keep it, or whatever works). A good commuter bike for example (no suspension) with skinnier tires will run circles around any mountain bike inside of the city. So there's something to be said about figuring out what your primary goal is and working out from there. Hard to gauge though, it took me a few different bikes before I found the sweet spot and it sucked selling off a few that weren't working quite right for me, but I guess that's like with anything. Try it out and evaluate and trade up if it's not quite there for you.
Check out pinkbike.com for a pretty large marketplace of used bikes.