Plans for building a scanning tunneling microscope (STM) for under $100 – “The goal of this project is to build a simple STM that can resolve atoms, with a cost of materials less than $100.00 excluding oscilloscope. My real goal here is to provide a base of information so experimenters and students could build a simple STM. Typical piezo tubes used in tube scanners of commercial scanning probe microscopes cost in the range of $200 – $800 and operate with several hundred volts applied to the scanner. This design uses a unimorph disk scanner to reduce the cost and avoid using any high voltage. The Piezo element is commonly available and this particular one costs $1.80. The control voltages are so low that two 9-volt batteries can power the control electronics.” – Link.