about to get my own smb, but curious about the price discrepancy. same features, orally-inflated/"x" length/exhaust valve, etc. but certain brands cos substantially more. apart from branding, does the superior, at least i hope, quality for the more expensive alternatives warrant the extra cost?

I have both a cheap one and another costing 10 times more. Both are of similar size and worked about the same way. The expensive one however, do have better inflation valve making inflating while underwater much easier and smoother task. Fittings are also better. It was a really difficult decision but I am quite glad I bought it!