While rug pads are not the most exciting part of buying a new rug, they are a good option to consider when purchasing a handmade rug.
First of all, do you really need a rug pad? The short answer, it is a worthwhile investment. The rug pad helps protect the rug, the humans and their pets. A pad keeps the rug from "walking" across the floor, which is can be annoying. But it also stops the rug from bunching up, which is a tripping or slipping hazard. Rug pads also help protect the rug from crushing and wear. Furniture can be heavy and causes the wool to compress. The pad helps minimize this. Every time we walk on the rug a small amount of wear occurs. The pad helps minimize this also. In the long run, a good pad will extend the life of your rug.
What type of rug pad should you purchase? There are a few choices and the one you pick depends on the type of rug, where it is located, how much cushion do you want or how much can you afford. A runner generally needs a thinner pad that maximizes the non-slip factor. These thin, non-slip pads are a fairly affordable option. A large rug in a living room won't move around very much but often has furniture on it. It will need a thicker pad but maybe not the non-slip property. This can be as simple as 1/4 or 1/2 felt, the most affordable option. A small to medium rug in a heavy traffic area might need both the non-slip and the cushion. This option is at the high end of the price points. There is also a specialized rug pad for putting rugs on top of wall to wall carpet.
What not to purchase! Unless you plan on replacing your non-slip pad every year, do not purchase these type pads from the big box stores. They use an inferior product that breaks down quickly, gets sticky and can ruin the finish on wood floors.
Finally, if you need help deciding, I would be happy to show you some samples and explain the differences in person. Or, you can go to your trusted rug cleaning company. They are the best resource for purchasing rug pads and they will cut them to fit. On-line purchasing is an option if you know exactly what you are looking for.