Was over at Dick's Sporting goods at Arrowhead mall yesterday and they carry Diamondbacks, some in the $300 - $400 range. I'd spend a little more unless you come across a great deal on a used MTB. The shifters are all plastic and don't look like they would last more than 2 -3 years.
For those contemplating purchase of ammo at this location they had little if anything in stock, and a sign that says "limit of 10 boxes of ammunition per customer". Not cheap either, $25 for a 50 WWB 45 ACP, almost $50 for a box or Remington 44 MAG and about $200 for a 200 round .223 - that's nuts.