Brian Krebs says the payment card data stolen by cybercriminals from the US retailer Target is being sold at low prices compared to the period when the information first emerged on underground markets. Thats because the number of valid cards is dropping quickly. According to the expert, shortly after the breach came to light, cards were being sold for between $26.60 (19.42) and $44.80 (32.71) per card on the Rescator.so website. Now, prices ranges between $8 (e…