A lot of watthour meters appear on ebay.  Most are removed from service, but occasionaly a "surplus" new one shows up.

NO, in almost every juristiction, you are NOT allowed to put your own meter on your house...the meter belongs to the power company...it is their cash-register!  Those few locales which allow consumer owned meters specify the meter must be independently certified for accuracy, and must be installed by a licensed meter service company.  You cannot count on a used meter being accurate unless it has been tested against a standard of known accuracy.

Meters can be useful for load-study, like a manufacturer putting meters on seperate feeders supplying power to seperate processes in a plant.

Often, old residential meters end up being turned into lamps.  Modification must be done on the meter to make it spin fast enough to catch your eye, as a 60W bulb in a lamp will barely make the disk turn.