$300 is market price for a .58 CVA Mountain Rifle. They are difficult to find.
The Spanish barrels are generally regarded as lower quality than the US-made barrels, but I've never seen a side-by-side comparison that upheld that impression. Also owners of the Spanish barrels are well satisfied with performance. Finally, finding a US-made barrel on a .58 Mountain Rifle is very difficult - they're quite rare. I wouldn't hold off on buying one with a Spanish barrel.
If you decide not to buy it, send me a PM.