Sheesh Charles!

You wrote;
"the seller's real intent is to locate new buyers and sends a list or catalog of additional items for sale along with the auction item looking for larger follow on sales without paying any auction fees.
Is this activity within eBay guidelines?"

Sending a new customer a sales list or catalog after making an initial sale is called doing business. ....sending an old customer from a previous eBay transaction new news about an item that they might want wouldn't be cutting anyone out of a transaction....

...if you might feel guilty about having bought chips from someone in the past that were the result of private transactions, tho' you gained knowledge of said chips because of their listing chips for sale on eBay, by all means! Send eBay a check for every transaction that you have made with that person!

Take care,
Bob