The photos are such that the dimensions of the bars are fairly measurable - I used an architect's rule that measures in decimals. The ruler in the photo helps. After correcting the measurements with the ruler (on my screen, the 6" ruler measures 3.8"), here's what I came up with.
Bottom width - 1.437"
Top width - .995"
Bottom length - 3.00"
Top length - 2.526"
Thickness - .75"
The average width is (1.437 + .995)/2 = 1.216"
The average length is (3 + 2.526)/2 = 2.763"
The volume for 1 bar is 1.216 x 2.763 x .75 = 2.52 cu.in. = 41.33 cc
The volume of 4 bars is 165.3 cc
The weight of 4 bars is 55.3 tr.oz. = 55.3 x 31.1 = 1720 grams
The S.G. = 1720/165.3 = 10.4
This calculation does not consider the depression on the bottom of the bar.
For some reason, I can't get the Ebay listing again in order to re-check my measurements and more closely examine the markings and the depression. If I properly did the measurements and calculations, what metal would these be made of? It is surely not gold. The S.G. of silver is 10.5. I have seen these paperweight replica bars made of gold-plated silver, gold-plated copper base, and gold-plated lead base. I have seen more lead base than any other type.
I would guess the bars are gold-plated silver or lead - probably lead. It could be some weird worthless alloy that I haven't considered. With the depression, the actual S.G. could easily be closer to lead - 11.3 - very possible.
Maybe the guy removed the auction and that's why I can't get it. Maybe someone suggested that he file into a bar and he discovered it was silver (or, most probably, lead).
My final guess is that the bars are made of lead.