Selling item at reduced cost without having “best offer” option

[mmjlrs-8]

Buyer wants to purchase other items and we agree on reduced cost. How to send an invoice? Can I pull items an invoice, do they need to put them in their cart? 
Second Question: If ebay identifies someone who is “watching” my item and I send reduced offer how do they get billed at reduced rate? Everyone keeps paying normal cost and I have to issue credit. Same with combined shipping. People claim ebay bills do the pay all shipping and I am making huge credits back. eBay penalizes for having to adjust account and issue refund. 
appreciate help.

[iart]

What we often do is set up a private sale.

We put in basic info, snatch a photo of anything, put an abbreviation of the buyer's ID in the title. Mark it all: "As Agreed".

There might be better ways but this works.

Your 2nd question sounds like a glitch. This does not happen to us. Are you sure the people buying are the same as the people getting offers?

[erkosuniverse]

Yes, iart,what you have explained is the way to go,I myself have done this in the past

Then the sale is correct in all aspects

Great post,iart😊