Since this started with a magazine, I'll ante up a magazine:
One Lahti-Saloranta 20-round magazine, new/unissued condition. This is the one seen on some Mosin and PSL conversions.
These mags officially take the Finnish 7.62x53R, which is basically the Russian 7.62x54R loaded to a slightly shorter overall length. There may be at least two variants of the Lahti magazine. Some take 54R with minor fiddling, some don't. I don't have any loose 54R to use to check this one with.
As far as actually getting them to fit in a PSL, it has been done both with a bit of welding and shimming and by using one of the old "rusty" PSL mags (which don't appear to be for sale any more) as an adapter. I've checked the fit in a Mosin, and it appears to go up sufficiently to present the rim to the bolt for feeding, but you'd have to fabricate the locating and latching bits.
update: since I had some SMLE parts laying on my desk, I tried the magazine with the Enfield trigger guard. With a little relief at the front of the guard, the Lahti mag would slide right in. So it might be useful for a 54R conversion.
Quantity available: 1
Price: free to the winning Gunco member. I'll pay the shipping too.
PM me with "LAHTI" in the subject line, and at the end of 7 days I'll roll my souvenir dice and count down the list to match that entry.