I've always taken that to mean
'this item would be cheap, were it half its actual retail price', which does make perfect sense, does it not?
( Monty Boyce, My cheese game is strong, Fri 15 Jan 2010, 10:23, 2 replies, latest was 16 years ago)

Makes sense,
just seems a bit of a redundant thing to point out. A bit like, "he'd still be alive if he weren't on the receiving end of that severe bout of Badger Rage."
(LongJohnBaldry, Fri 15 Jan 2010, 10:32, Reply)

HA!
*clicks*
( TGB checking Off Topic is still shit at, Fri 15 Jan 2010, 10:35, Reply)

I agree
but I have heard people use it wrongly (is wrongly a word?)
( Colonel Dracula Two manky hookers and a racist dwarf, Fri 15 Jan 2010, 11:01, Reply)