I think 8-12v on an 18v pack might not be super comforting. Doctorbass rejects all packs under 12.5v (Of course, you're also selling for 66% less $). So these packs are 5s right? If they're 8v, how many cells are they supposed to have that are above 2v? I can't imagine many cells go below 1v, so you're talking about at max having 4 cells above 2v (1+1+1+2+2=7v *2 because they're 2p). For $5 you'd be getting 1300mah*3.7v*4 = $.26/wh. Actually, that would be quite nice, but I'm not sure how likely to expect 4 cells still delivering 1300mah from an 8v pack.
My guess is just that people are less clear what to expect from 8-12v packs. Have you had luck with these before or do you know of someone having luck with them? If someone is lucky, this could be actually a decent deal (I didn't realize until I did the math above). Personally I have a bit too many projects on my hands right now, but I think the only reason no one has snapped this up would just be that wavering sense of confidence. Or that they've only been for sale for a short while.
New to endless-sphere? Notice a lot of signatures recommending Ebike.ca? That's because it's the best place for a quality and manageable, (but still 'real'), first build. Justin is a solid supporter of electric bike development, and a good source of equipment.
My hat off a thousand times to the green people that effectively run this forum. The ES Mods are superb.