Gifts from uninvited guest?

We made a simple rule that we weren't allowing new bfs/GF that were less than 6mos old, and no guests that BOTH of us don't know. The main purpose was to keep our wedding intimate. My friend and her very new bf (whom i didn't invite) just sent me a super expensive gift off my registry. I feel so bad now... it was a super generous gift (it's a dyson if you must know), and she sent it to me almost a month before my wedding. I don't want to invite him just bc of the gift.. (I have told her I would like to meet him one day). I've also told a few others about our rule, and that would mean I have to invite them too. Would a thank you card and phone call be enough? Or taking them out to dinner? Just feel kinda weird about it, didn't expect it. Guess this is what I get for being so strict about guests. ?