I want to buy a good mountain bike?

In my experience bike shops don't deliver, they expect people to come in, test a few bikes, ride around and get "fitted" properly. Then they put the screws to you like a car dealer and try to sell you whatever overpriced crap they think you can afford. The only way to do it without getting screwed is research what you want, go into the bike shop and tell them to order it for you. I bought my bike on eBay.