Comet Hale-Bopp was discovered at the same time by Mr. Hale and Mr. Bopp. Objects that were named prior to the formation of the IAU still retain their names. It's your money. It will be just as valid. All you need is a printer and some nice paper.
Flowers are romantic.
Wine, a fine meal, a stay in a fancy hotel, any of these would do nicely also. Also, many public institutions like observatories, zoos, and museums have fund raising opportunities where you can make a donation in someone else's name. That person is then honored with a plaque on the wall or an engraved paving brick in a walkway. The advantage here is that your money goes to a good cause which will be of benefit to everyone. In addition, it's a lot easier for the family to go see their loved one's memorial brick than it is to see one of those extremely faint stars.