Would it be a good idea to buy a large 4-5 lb. roast to leave in the fridge to dry age (only a few days for the purposes of storage) and then take a steak slice every time I want to eat from it?
Some suggestions: rump roast, London broil, or round roast. I can get these for under $10/pound, as a guideline. Try a smaller roast (1.5 - 2 pounds) from that region (rear part) of the beef. There, you will find large-ish expanses of lean meat, the best for chewing without running into sinew. Don't worry about aging your meat so much as finding out if you like a cut in terms of chew-ability. Remember, the mechanics of taste and chewing are very good because they signal the digestive tract to start digesting what's coming along.
If you decide to age some beef, you can do it on a plate, just turn the meat over so that it doesn't slime up. You can learn more about hanging and aging meat on this forum if you search
hanging. I learned about it mostly from van, iguana, and sabertooth. I eat the dry outer part of the meat and every bit of fat.
I usually age a ~5 pound whole eye of round, untrimmed, from a stainless steel S-hook on the bottom of my fridge, probably not a tactic you can do if you share a fridge with your family.
The better-prices on pastured lamb will be in the cheaper shoulder chops. I get a whole lamb, and I gnaw most of it off the bones - I know, quite cavewoman-ish.
It's also good to eat marrow out of the long bones, such as femur (thigh) and humerus (arm).