Anywhere from $300 - $1000 for a decent condition 2nd hand (depending on model)
Easiest way to recognise? well there should be obvious visual differences, but they should have tags of authenticity stating the model.
Side mount- fixed, bottom mount- reclinable
Sources - Jap wreckers eg. SSS, JustJap (Syd) or Importbitz.com, or any reliable importer like AE86T (Wei)