wlf, satin, you're clearly men after my own heart. Wonderful design, my favourite dagger (and I love daggers above any other type of knife).
wlf, those ones for $5 were pakistan-made things. Amazingly some actually looked quite good if you were lucky. I do have one of each type (the black painted blade, the all-chrome, and the chrome blade/gold handle) of those, a 3/4 size one (stunning piece of workmanship, I'd rate it higher than most SOG daggers in all honesty), a J. Rodgers one (made to 3rd pattern spec - O1 steel blade, alloy handle and guard), a R. Cooper one, a J Nowill one, (again third pattern, this time in all Stainless steel), half a dozen others with no names (various markings, all commercial pieces, two with stinless blades, the others with various carbon non-stainless blades) all 3rd pattern, and a wilkinson sword current repro of the 1st pattern (the best looking of all three). Unfortunately Wilkinson decided to make these with stinaless blades instead of proper high-carbon steel, but other than that they're perfect replicas.
I don't own any of the original war-issue ones (although you can get a 2nd or 3rd pattern (issued, with inspectors mark) for $100-$200 on ebay every so often), just seem to keep buying other knives in between them coming up for auction.
Satin, the J. Rogers one is a proper use one. Made to true WWII military spec, and perfectly usable as long as you don't try to use it outside it's original design. And the "brittleness" wasn't a flaw. They're designed purely for piercing the throat or going through multiple layers of clothing and into the kidneys. The "brittleness" myth was caused by US soldiers being given them and then trying to use them to open beer bottles, carve thier names into tree trunks, and so on.
As for the ultimate F-S dagger, it'd be 1st pattern, Talonite blade, stainless steel handle rather than the somewhat light "white metal" alloy originally used.