Amazon just turned up the heat in the grocery wars with Walmart and Target

• Amazon Prime members can now get unlimited grocery deliveries for $9.99 per month.
• Shoppers can get free delivery on orders over $35 from Amazon Fresh, Whole Foods, and more.
• The cost is still higher than comparable offerings from Walmart and Target.

Summer is approaching, and the competition for same-day grocery delivery is heating up.

Amazon is now the latest major retailer to enter the fray with a new subscription option for Prime members to get unlimited delivery on orders over $35 from stores, including Whole Foods, Amazon Fresh, and other local shops.

Starting Tuesday, Prime members can sign up for a free 30-day trial of the $9.99 a month service, and customers with a registered EBT card can use the service without a Prime membership for $4.99.

"We have many different customers with many different needs, and we want to save them time and money every time they shop for groceries," Amazon's senior vice president of worldwide grocery stores, Tony Hoggett, said in a statement.

The news out of Seattle follows a similar offering from Target, which launched its Circle360 membership earlier in April for an introductory price of $49 a year.

And the highlight of the Bullseye's first-ever paid membership option? Unlimited free delivery of groceries (and other stuff) via the company's Shipt service on orders over $35.

Of course, both are following the course set by grocery juggernaut Walmart, whose $98-per-year Walmart+ membership includes grocery delivery among its perks. Walmart, like Target and Amazon, requires a minimum purchase of $35 for the free delivery option. Walmart also offers a half-price option for qualifying recipients of government aid.

The company will even have a blue-vested associate put your produce and perishables right into your fridge for an extra $7 a month.

At $259 a year — between the $139 annual Prime membership and the $120 total delivery membership — Amazon's offering is by far the most expensive of the three companies.

Even so, considering the fact that 75% of shoppers already have a Prime membership, that all-in number might not make much of a difference.