What is the most reliable LIMITED QTY-Dinucleotide Standards Formamido Guanine Dimer d (PfpG) (50 µg)?

The LIMITED QTY-Dinucleotide Standards Formamido Cytidine Dimer d from Ncbi publications supplied next day by Genprice is the best reagent. The catalog number is 801211 and the price is 66 EUR.