Australian International Arms made a few hundred x39 and a few hundred 308 new-manufacture SMLEs back 20+ years ago or so. As I understand it, the 308s went to Canada and the x39s went to the US. I spent years looking for a x39 and finally found one a decade or so back. They nominally feed from AK mags, but in practice I found it almost totally unwilling to work with anything but the factory 10rd mag.
Accuracy was..interesting. Seems they used .308 spec barrels rather than .311, and that led to wildly varying results. I threw a Leopold Mk4 on mine and found some steel cased loads that were right at 1 MOA for 5 rd 100 yd groups...and other loads (including good brass cased US ammo) that were 10-12 MOA.
Who the hell knows what you'd pay for one if you found it now...$1500 maybe more. I'd expect the search to take years, and you'd need to be willing to pay any asking price without hesitation, because there's just aren't many around.