Seller changes item after 'offer' is accepted

This seller has changed the items in this auction after the auction has finished. Bundle included PS4 VR set + 11 PS4 Games.

<<< I DO NOT WISH TO START A DISPUTE _ BUT WANT TO KNOW WHERE I STAND & WHAT IS FAIR  >>>

During the auction, the seller requested I make an offer.  They accepted my offer of $300 and requested payment - I confirmed that I wish to pick up & pay cash.

The seller then emailed me that only 4 of the games are left as have been given to friends - the lesser value games of the bundle that was listed.  They offered a reduction of $10 per missing game or $270, or a free PS4 controller if I agree to the full $300.

I don't believe either of these is a fair offer.   I think the games that were listed would have been worth more than half the value if all items were purchased new.  The full bundle that had been listed as part of the offer I made and that was accepted - is now only half available. Is it unreasonable to ask them to get the games back from friends - as they had been sold to me?  Am I correct that once my offer was accepted, then legally the auction is binding?

I still want a VR set, but I made the offer based on the games that were listed - where do I stand?