Some of these folks have been tanning for twenty to thirty years. They are teachers, peers, friends or simply talented people with something to offer. Keep in mind that most of these folks are home producers rather than industrial magnates and may not always have what you want in stock. It may take a call or two, but you should be able to find what you are looking for. You will notice that each person is listed as either wet scrape, dry scrape, or both.
Wet scrape is when hides are scraped with a dull tool, wet, over a beam.
Dry scrape is done by drying the hide out on a frame and shearing off the hair and grain with a sharp tool. Generally, dry scrapers scrape down to where the bigger, mature fibers are. So the hide has a knappier surface. The process and product are slightly different but not much. There is probably someone near you who teaches tanning classes.