A bike is a good way to go,, but your budget is very low. The good bikes that have the real fat tires (they can go through sand even) well those are not cheap New ones are in the 2-3K range.
Now what does not make a lot of sense to me is you're asking about a mini bike or a off road go-Kart and these need to be carried in a truck from home to the Ranch, field, or BLM or WMA area.
But anyway Christmas time is coming and things get put up for sale on Craigslist by folks that need extra cash.