No cars please!
You are too generous by far!
I have discussed the matter with my beloved Felicity and we both agree that we cannot let you buy us these cars. Your generosity is most endearing but we would really prefer something a little more modest and practical, perhaps an electric waffle maker?
In all honesty we will be just thrilled for you to be there and get far more pleasure from your presence than you presents! You are sort of one of the family now.
The invitations are at the printers. I will send one to you as soon as they are available. What address should I use? Will you be bringing a friend?