buy up - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Purchase all that is available, as in They want to buy up all the land in this area. This term was first recorded in a law enacted under Henry VIII: “They buy up all manner of fish.”