There are lots of monopods out there that cost under $100 and you can get just about anything if you['re looking under $200.
The
Vanguard elite Carbon Fiber monopod is only $89. Carbon fiber means it's light yet very stiff.
The
Manfrotto 681B is an aluminum monopod at around $60.
They're in the 63-65" range extended, but by the time you add a
small ball head and mount the camera, that adds another 6"-8" or so to the height of the eyepiece, which moves it up to around 6ft.
If you want something taller, so that even if the base is in a hole or lower on a hillside it's still tall enough, look at the
Gitzo GM3350XL. It has an extended height of 73", so add on about 4" for the camera and if you use a ball head you can add another 3-4".