I do not have access to the current market prices of specific stones. However, generally speaking, porphyry is considered a high-end material and its price may vary depending on its origin, color, and quality. Rittner Porphyry is a type of porphyry that is quarried in the Italian Alps and is known for its durability and unique reddish-rose color. Therefore, it might be safe to assume that Rittner Porphyry is likely to be on the expensive side. Nonetheless, the ultimate price of a particular stone will depend on several factors and may need to be determined via inquiries with local stone suppliers or consulting with contractors.