I visited Jazzproparts shortly after a thread came out earlier this year. Although they are not as large as some of the other JDM suppliers in Dallas, they are the only ones carrying Nissans RB engines. They also had an assortment of SR engines along with numerous Toyota and Honda motors. From what I saw their motors were very clean and undamaged. Most still had their trannys bolted up and were secured on wooden pallets. I was told that they rec a container of motors monthly. It was also explained to me that they were more interested in volumn, that is why their prices were so much cheaper. I can only assume that your inquiry might have come between shippments. That could explain their short supply.
For what it is worth, I am planning on buying two RB 25 DETT's from them in the near future.