Apple's often-rumored tablet may need to come in well below the rumored $800 price if it hopes to attract Windows users, a study shows today. While Retrevo believes 68 percent of Mac users are willing to opt for the large multi-touch device if it costs over $600, only 36 percent of Windows users asked would agree to the same terms. The difference is similarly wide at $800 where 41 percent of Mac users would pay $800 or more while just 20 percent of Windows users would agree to the same terms.