I tested two types of aquarium digital thermometers with probes at a friends store. Three of each type by same distributor costing 25 and 40 dollars, all brand new in stock. They are similar to if not identical to some that are sold at Radio Shack.
They varied in readings by up to 4.5 degrees with no particular pattern. Three of them were within .5 degree of each other and my Kodak 14" mecury thermometer. I don't know about $120.00 digital thermometers but it seems to me that these digitals give one a false sense of accuracy. Besides, isn't consistency more important than absolute accuracy?