I'm not up on Apple I values, but if I recall Apple Is have sold for a couple hundred thousand before - they came with all the original paperwork though.
This one is almost certainly not worth as much as is being asked, though it's probably worth a low to mid-5-figure sum.
I think collectibles in this value range should be purchased from a knowlegeable dealer or auction house - not ebay. You have no idea if this seller is on the level. The seller doesn't even include an appraisal letter or any other documentation that can prove its authenticity - if you're asking this much you ought to be offering some documentation with it.
Finally, as pointed out above, an Apple I is probably not that hard to fake as it used conventional, off-the-shelf components. I'm sure it's been done.