Want to own a little piece of heaven? It's yours, starting at $19.99 an acre--on the moon. If you prefer, you can buy property on Venus--or Mercury. Mercury is nice this time of year.If that's still too close to the hustle and bustle of Earth, there's Mars--33.9 million miles from Times Square. A deed, with your name on it, to a prime-view one acre lot on Mars will set you back $22.49, plus tax, plus shipping (not from Mars) and handling.The man selling these lots is Dennis Hope, founder and owner of Lunar Embassy Corp of Gardnerville, Nevada, which claims to hold the property rights to several heavenly bodies. How many? "Nine altogether," says Hope brightly. "When we started, Pluto was still considered a planet."