A barebones generally includes a case w/ power supply, a motherboard and a floppy drive. Anything much beyond that and you're into the individual needs/personal preference territory. Some also include a cheap kbd and mouse - that's up to you. I think the kbd, mouse and screen are the ones that make the most difference in user satisfaction - so I'd leave the kbd/mse up to the buyer too.
. It really depends on your target market. Trying to come up with specifics is pretty much a waste of time without a target market in mind.
. The one that Rib came up with is a pretty high-end starter box. Rib must be independently wealthy (from this and other recommendations I've seen

...).
.bh.