Rtc, ethernet, and usb would be highest on my list, even just ethernet and rtc would get me what I need.
Edit: Price would need to be altered depending on features, I selected the $50-$60 but that may not be enough. Basic usb hub might fit in the $50 range, but add more features and price probably needs to go up depending on expense. Even if a third party is soldering everything, you still need to package and ship, and that can be a hassle! Price needs to overcome hassle.