Dobsonian telescopes, or Dobs, are a type of Newtonian reflector with a low-cost altazimuth (AZ) mount and other parts that facilitate large apertures and portability. This design lends itself well to DIY. The two designs for Dobsonians are closed tube and truss (open) tube. Truss tube designs generally start at around 10" or so and up so that they can be taken apart, carried, and fit into vehicles for transport.
Prices can be misleading - some vendors offer extras like a shroud for example while others are bare bones. And none include eyepieces so you will need to spend additional money to get a functioning system. Dobsonian telescopes are suited for visual astronomy (and not so much for astrophotography).