Don't sell at all. I think you'll not able to collect everything you want again, later.
I'm a proud father of two, with less freetime than ever, but I reject to sell anything although I have absolutely no time. My son become 3 yrs old and since he was around 20 months old he wants to watch Superfrog every day, as he saw the intro once way back. 3-4 years are just flies, and soon kids becoming quite interested about all gadgets - can be anything better than an Amiga to start live with? On CDTV we're having some minutes recently with Fun School III, it's quite entertaining for him, so if the weather isn't good enough to play in the garden we can jump into the front of that.
Don't sell... don't waste anything you had, just because you afraid of lack of free time for it.