I wanted to get into MTB without spending a fortune to make sure I liked it (stupid me). I bought a Fluid Renegade from Anaconda for about $600.
Not going to win any prizes for the flashest bike, but I raced it and trail rode for a year and it was solid as a rock and very reliable. Nothing broke, regardless of what I hit (and I hit lots as a newbie).
Came with a basic 100mm fork, shimano disc brakes, Deore gearing and shifters. Very basic kit, but all that was required for a newbie. I guarantee you will turn your first bike over quickly, so don't spend heaps, just get something that will be reliable and get you out riding.
Anaconda always have 20% sale days. I waited for one and picked up a capable bike cheap.