FWIW (monoprice live chat):
you: Hi Joseph. There is speculation about some sort of credit card breach at a couple internet forum sites where Monoprice is often times recommended. Is there any cause for concern?
CS - Joseph B (Level 1): A few of our customers recently reported to us that information from credit cards they used on the Monoprice website had been misused. We promptly began an investigation with the help of expert computer forensic investigators to determine if any card data had been stolen from our computers.
CS - Joseph B (Level 1): To date, the investigators have found no evidence that card information has been stolen from Monoprice's computer network. As a precaution to ensure that our customers' information is not at risk, we have taken our website offline temporarily while we and our investigators complete the audit of our computer network.
CS - Joseph B (Level 1): We want to ensure that there is no security vulnerability in any part of our computer network system. We notified local and federal law enforcement agencies, our credit card processing business partners, and all credit card companies that some of our customers reported concerns regarding their card information to us.
CS - Joseph B (Level 1): We also advised these entities that we are working with outside security specialists to determine if there was breach of our computer system. We will post additional information when it is available. We regret any inconvenience that our investigation and the temporary suspension of the Monoprice website may have caused you. Thank you so much for your great support.