I have a steel Marin Muirwoods 29er - cost me $415 back in the day.

Its marketed as an urban bike but since it has a MTB-tough frame, it can handle fire roads as well pot-holed urban streets.

You can find them on Amazon and eBay. Had a rigid fork but I actually prefer it since I upgraded it to take wider tires, they provide all the suspension I really need and then some.

Its a good value.