I just bought a Sable IV, am I crazy? I've wanted one since they first came out. Couldn't afford one at the time, as it was something I'd only get limited use out of. But it seems like they keep going up in price and getting harder and harder to find. I justified it as a good investment. Those of you who own or collect OPKs--what do you think of the Sable IV? will they keep appreciating in value? How are they to use in the field, etc?