You are submitting requests too quickly

Created a page with a table that includes 24 product ads for books that are recommended reading by our 501(c)(3). Was formerly using astore.

My php error log is getting filled up with these errors:

<h4>You are submitting requests too quickly. Please retry your requests at a slower rate. For more information, see Efficiency Guidelines.</h4>

These errors seem to accumulate every time someone visits the page. Additionally, many times when visiting the page, not all of the products show up and one must refresh to make them appear.

I am speculating that every time someone brings up the page, all of the products are downloaded from Amazon, unless it is within the 30 minute cache expiration period? Am I correct?

Is there any way to change the cache expiration period or is there a better way for me to present these items so as to improve performance and eliminate errors?

The page I need help with: [log in to see the link]