Question: For travel convenience, I prefer to print posters near the conference location. How can I efficiently look for the best poster printing price near a conference location?

(In my experience, conference organizers sometime point to a printing business, but they typically tend to be not price optimized, far from it)

Answer: 
First off, avoid the print shop at any conference location, which is quite likely to be both overbooked and expensive.

Second, make sure to send your poster far enough ahead of time to avoid a potential last-minute rush (particularly at large conferences).

Finally, you can use Internet map sites (Google Maps, Apple Maps, etc.) to search for copy shops near the conference location, and call to find out their rates.
If you are in the United States, phdposters.com has local pickup in Baltimore, Boston, Brooklyn, Denver, Durham, Richmond and San Francisco, usually in a university library. Their rates are also pretty reasonable.