Honestly it is very difficult to make prime rib at home affordably. Prime rib is an expensive cut of meat and unless you live in a large city where finding a quality butcher is even plausible you shouldn't try. If you do have a good butcher go for dry aged beef. 4 weeks is good 6 is better. (dry aging adds more of the delicious beefy flavor) If you are buying this in a grocery store, stop, get something else, their prime rib is anything but prime, you'll be buying a pound of fat at a high cost. But if you do get a nice piece of meat here is a recipe that I like quite a bit. Prime Rib Au Poivre feeds 8 ingredients 1 9-pound prime rib beef roast (about 4 ribs), excess fat trimmed 2 tablespoons Dijon mustard 4 teaspoons minced garlic 2 tablespoons plus 1 teaspoon mixed whole peppercorns, coarsely crushed 1/3 cup minced shallots 3 1/2 cups beef stock (homemade is best) 1/3 cup Cognac could also use madeira or red wine preparation Position rack in center of oven and preheat to 450°F. Place beef, fat side up, in shallow roasting pan. Sprinkle beef with salt. Mix mustard and garlic in small bowl. Spread mustard mixture over top of beef. Sprinkle 2 tablespoons crushed peppercorns over mustard mixture. Roast beef 15 minutes. Reduce heat to 325°F. Roast until meat thermometer inserted into center of beef registers 125°F. for medium-rare, tenting loosely with foil if crust browns too quickly, about 2 hours 45 minutes. Transfer beef to platter. Tent with foil to keep warm. Pour pan juices into 2-cup glass measuring cup (do not clean pan). Freeze juices 10 minutes. Spoon fat off top of pan juices, returning 1 tablespoon fat to roasting pan. Reserve juices. Melt fat in same roasting pan over medium-high heat. Add shallots and sauté until tender, scraping up any browned bits from bottom of pan, about 2 minutes. Remove pan from heat. Add beef stock, then Cognac (liquid may ignite). Return pan to heat and boil until liquid is reduced to 2 cups, about 15 minutes. Add pan juices and remaining 1 teaspoon crushed peppercorns. Transfer pan juices to sauceboat. Carve roast and serve with juices. You can grill this as well using the same parameters when thermometer hits 125 you're done, you might want 135. Serve with some kind of potatoes and caramelized brussel sprouts

Buy a prime rib at any grocer and the trick is to brown it first by putting it in a 450 or 500 degree over for a short period of time (1/2 hr) then turn the oven down to 325 and bake for 1/2 hr per pound. Of course you want to put a rub on it or just plain salt and pepper to flavor it.

There is a very good article here that explains all the details on creating a good prime rib. Good luck!