Alas, with Herself near at hand, I don't think life would be worth living were I were to bring your 550c into the house, but it looks like you may have found the source of your own 550c troubles.

The fact that it is boxed and more or less mint does, however, makes it very attractive, even at the price (which is not unreasonable, given what you have).

Good luck with the sale. I think probably eBay is your best bet, as a great many of those posting here are young people, for whom the price of any 550c is just going to be too much, though for rather different reasons than myself!

My hunch is that you'll get a flood of offers at the last minute. I hope it goes to someone who can appreciate it.