(Whole Foods/Facebook)

Whole Foods just got less expensive.

On Monday, the day that Amazon's $13.7 billion acquisition of the grocer went through, prices on certain Whole Foods items immediately dropped.

"Starting Monday, Whole Foods Market will offer lower prices on a selection of best-selling staples across its stores, with much more to come," the companies said in a press release on Thursday.

In the release, Amazon and Whole Foods specifically mentioned certain items that would become less expensive when the acquisition was finalized.

On Friday, Business Insider visited a Whole Foods location in the Gowanus neighborhood of Brooklyn, New York, and checked the prices on 15 items (including a few variations on similar items) mentioned by the companies. The total cost of the basket on Friday — pre-acquisition — was $97.96.

(Kate Taylor/Business Insider)

On Monday, we returned to the Gowanus Whole Foods and checked back in on the same items. This time, the total cost of the 15 items was $75.85. That's a nearly 23% drop in the total cost.

Some of the new discounts nearly cut prices in half. Bananas, for example, used to be sold for $0.99 a pound. Now they cost $0.49 a pound. The price of local grass-fed 85% lean ground beef went to $6.99 a pound from $10.99.

(Kate Taylor/Business Insider)

Whole Foods is labeling the price cuts as "New Lower Price," with the tag "Whole Foods + Amazon."

Here's how much money customers are now saving on these 15 items:

• Whole Trade Banana: 50 cents (Price dropped to $0.49 a pound from $0.99)

• 85% Lean Ground Beef: $2 (Price dropped to $4.99 a pound from $6.99)

• Local Grass-Fed 85% Lean Ground Beef: $4 (Price dropped to $6.99 a pound from $10.99)

• Four-pack of Organic Avocado: $0 (Price stayed at $6.99 for a pack of four)

• Hass Avocados: $1.01 (Price dropped to $1.49 each from $2.50)

• Organic Large Brown Eggs: 30 cents (Price dropped to $3.99 from $4.29 for a dozen )

• Fresh Atlantic Salmon Fillet: $5 (Price dropped to $9.99 a pound from $14.99)

• Frozen Atlantic Salmon Fillet: $0 (Price stayed at $10.49 a pound)

• Fresh Tilapia Fillet: $4 (Price dropped to $7.99 a pound from $11.99)

• Organic Baby Kale: 50 cents (Price dropped to $3.49 a pack from $3.99)

• Organic Baby Lettuce: 50 cents (Price dropped to $3.49 a pack from $3.99)

• 365 Brand Almond Butter: $1 (Price dropped to $6.99 a jar from $7.99)

• Organic Fuji Apples: $1.50 (Price dropped to $1.99 a pound from $3.49)

• Organic Gala Apples: $1 (Price dropped to $1.99 a pound from $2.99)

• Organic 365 Brand Butter: 80 cents (Price dropped to $4.49 for four quarters from $5.29)