Ceiling Texture Matching
That particular texture isn't in my "bag of tricks" either. It looks like a knockdown of some variety where the mud is sprayed on with a hopper and "knocked down" with a broad knife. I could probably get something real close, but it would take some trial and error. If you were to attempt this yourself, you'd have to invest in purchasing or renting the necessary tools, spend time experimenting with getting the pattern, and figure out how to "blend" into the existing. I agree with hiring it out. It's probably a common texture in your area.....
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