1934 Martin 000 Acoustic- This guitar is one of the rarest and most valuable instruments in the world period. Fewer then 100 Martin guitars were made during the 1930s are considered to be the finest acoustic guitars made in history. This particular one is the only burst colored guitar to leave the factory that year. Acoustic guitars come in different sizes. The most common are: 0, 00, 000, OM, Dreadnought, and Jumbo in order from smallest to largest.