Whats a slide rule or calculating machine worth?
There is no price guide for these items so shop around. Prices vary greatly but tend to be much higher on the net. Straight slide rules of typical lengths are generally quite inexpensive (free-$40). Circular devices in metal casings like the Fowler tend to cost more and the cylindrical models can cost hundreds or thousands of dollars. Cardboard slide rules often designed for special purposes are generally under $5. Calculating machines vary from free to thousands of dollars depending on model and condition. I don’t have pricing data on specific models but four function calculators generally sell for much more than adding machines. Even huge classy-looking adding machines with glass sides tend to be plentiful and sell for well under $100. The cheap-looking stylus driven machines are plentiful and generally cost under $7. Curtas generally sell for $70-$700 depending on whether the seller knows how collectable they are.
