It's a great piece of American history, $2 is a fair price for one, they are very common and typically found more readily than most other bottles from the same time period.
Back then there was no refrigeration and food, particularly meat, was preserved by salting, pickling, drying, or smoking - none of which could be said made the experience of eating enjoyable (compared to fresh meat immediately cooked over a fire at least). Soaking ketchup into the food, which was often very dry or nearly rancid, made it juicy and tasty for pennies, as such ketchup, as well as other similar condiment bottles, comprise a large percentage of 19th-early 20th century trash found at campsites and homesteads.
The stereotypical image of a cowboy eating beans from a can is often accompanied with ketchup on those beans, and there was even a receipe in the Great Depression for soup made from ketchup mixed with hot water, and that was the entire meal. So the humble ketchup bottle, though common, is a quintessential part of our nation's history, and if that's not worth $2, I don't know what is.
