Where do they sell INDOOR lamps that look like streetlamps?

Home Depot and Lowe's have lots of variety. Almost every city or town of size has at least one store and all they sell are lights, lamps, and every thing in between. You can go on line and put in "lighting" and then you just go through and find the retail store that sells only that; not like HD or Lowes, who sell a bunch of other stuff too. They will have what you are looking for within the price range you indicated. To get an actual street lamp you will have to go through a construction company and then if it is the real deal it has to be installed by a electrician and you might even need a permit from the city to have it installed, inspected, approved, etc.