I have a low pile Mohawk carpet with a subtle pattern cut to a 9 X 12 area rug in my living room. It is wearing like iron. This is a room we spend a lot of time in. Take some pictures of the room to a carpet store. Look at their remnants first as they will be the least expensive option. If none of them look right, move on to their stock carpet and then to the special order items. Mine was a special order, but not inordinately expensive. Be sure to bring home samples before committing because colors don't look the same at home as they do in showrooms. And as Beverly said, there may also be off the shelf 9 X 12 area rugs that would work. Just because the chairs are patterned doesn't mean the rug also can't have some pattern. If there is a good salesperson at the carpet store they can be a lot of help.
If you want to try a rug you find online, order the smallest size to see the colors in person and be able to return it more easily (for less money - no extra shipping charges) if you don't like it.
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