The Rock strikes me as a Korean refinish, possibly re-stocked here. If its in good mechanical condition, I don't see any problem with the price. In the not-too-distant future, one like that will go for twice that price. Very similar to 1911 rebuilds which in the last five years have carved out their own niche in the collectable arena, going for $1200 or so. Many of those are undocumented with no arsenal marks and possibly were rebuilt/refinished at other levels of maintenance than the arsenal rebuild programs and so were not marked. You just have to be knowledgeable about the carbines and pistols to hopefully avoid a 'home job', but the rebuilds do get blurry and next to impossible to read sometimes.