You've been seriously misled. I was at Costco this past weekend and I checked out a couple of mountain bikes they were selling for about $220. I don't remember if they were Infinity brand or not. Those bikes were as bad quality as you can get in a new bike - comparable to what you'd see in Walmart. Way too heavy (felt like it was over 35 lbs.) and full of cheap, easily-breakable plastic parts.

That said, if you are a casual rider that isn't too concerned about riding fast or having a bike with responsive components that shift accurately, it may be good enough for you. Be aware, though, that these bikes are a waste of time to upgrade. So if you start to get serious about cycling, buying better components to slap on your bike is like putting Chanel No. 5 perfume on a 70 year old hooker.