Online delivery service ShopRunner wasted no time attempting to take advantage of Amazon Prime's $20 membership increase and spirit away some of the online retailer's customers.

The company is offering Amazon Prime members a free 1-year membership that includes free two-day shipping of products purchased at select retailers if they jump to ShopRunner instead of renewing their Prime subscription.

"Welcome Prime members. We heard about the recent price increase and wanted to help. ShopRunner offers the same Unlimited Free 2-Day shipping you love, and much more. Plus, our promise to you: we won't charge you more than $79 when your free membership renews in a year and we won't charge your card automatically." ShopRunner said in a statement on its site.

Amazon's $20 increase brings an annual subscription to $99. The company cited increased transportation costs for the hike and also noted that this is the first time it has increased the price since the service was rolled out in 2005. Prime members receive free two-day shipping, free viewing of 40,00 movies and TV shows and the ability to "borrow" from Amazon's online Kindle library of 475,000 titles. The price for Amazon Student was also increased from $10 to $49, but the $299 Amazon Prime Fresh service, which includes grocery delivery in select markets, remained unchanged.

ShopRunner is a delivery service that works in conjunction with 85 retailers. A customer makes a purchase on a site and then chooses the ShopRunner delivery option. The annual membership fee is $79 or $8.95 per month. Participating retailers range from AutoZone to Bare Necessities. There is no minimum order size to qualify for free shipping.

ShopRunner does expect those wishing to leave Prime to prove they are members, but to help welcome these folks with open arms, the site has provided step-by-step instructions to find their proof of Prime membership:

1. Go to www.amazon.com/gp/primecentral

2. Log in if necessary

3. Click on "View printable receipt"

4. Copy the full receipt.  

5. Open a new email addressed to DoneWithPrime@ShopRunner.com 

Paste the receipt into the body of the email and hit send. 

Make sure to send it from your ShopRunner registered email address.

6. Paste the receipt into the body of the email and hit send. 

ShopRunner CEO Scott Thompson previously headed PayPal and he even had a brief stint at the top of Yahoo.