Paul, 20 acres is just right to support a 1.5-2 acre pond in your area...that is "if" the watershed flows right, you should have close to 40" annual rainfall. You don't have a problem if you buy an established pond, but you're going to pay a LOT more if quality water already exists. If you go that route, pay more attention to the water depth, natural structure, and most of all watch for drainage/leaky pond, you want a depth of at least 12 feet. The last thing you want to do is buy in late Spring, only to find that in August your pond is 1/2 it's size. Look at the prices quoted on this site for building a pond, it's not cheap, or guaranteed to hold water. But, if you do your homework, building is the way to go. First, start out by checking out all the small newspapers/real estate offices. It's not uncommon to find property that needs to be developed. The cost of bringing in a dozer to construct a dam is around $60 per hour, and you have excellent soil/clay throughout your area. If you find land with a draw, you could do it for 5-7 K easily...adding a LOT more than that to the value of your land, if you have the patience and time.