Hello Giacomo,
Miyanaga is a respected brand in the US. The American retailer, Japan Woodworker, sells Miyanaga blue steel laminated to wrought iron, handled in white oak, for typical prices of $80 (9mm) to $108 (24mm). You can look them up at
www.japanwoodworker.com. I have a few of these and they are fine chisels.
The ebay seller is offering white steel chisels, laminated to low-carbon steel (not wrought iron). These would be a less expensive item than what Japan Woodworker sells. However, the prices listed at the Ebay seller's store for the red oak handled chisels are excellent for the quality, and I would say these chisels are a solid buy at those prices.
"White paper" steel is simply a high-carbon steel, forged very hard, while "blue paper" steel is alloyed with chromium and tungsten. The 'white' and 'blue' simply refer to the color paper that Hitachi uses to wrap the sheets of steel.
Please note that that these chisels are in a regional Japanese style, where sizes from 3mm to 12mm are square in cross-section ('firmer' style). They are not bevel-edge. I mention this so you won't be surprised.
Wiley