I think you have to work out if you really need an MTB. They are great tools, but only if you do a significant amount of off-road riding. If you're commuting on the roads or on good quality tracks, then a hybrid or road bike will be lighter, faster and better value for money. With an MTB you spend out for the suspension, robust frame, chunky wheels and tyres etc, but you just do not need these on the road. A hybrid or city bike with a rigid front fork and slick tyres will be lighter and faster on the roads but strong enough for light off-road use, and will soak up the worst of the bumps too. A road bike will be faster still, but with skinny tyres you'll feel the bumps more. Some hybrids (with UK prices) at the link below as examples of what's available over here.
I don't know Avanti or Fluid, but GT and Giant are both very reputable brands.
