The FU-RGB went out of stock earlier this week. The number of people who were still after a board was more than anticipated. As such a new batch has been ordered. This new batch is not going to be as large as the previous batch. As such the price will also be increased.
Why the increase? Smaller batches cost more per unit to produce and the cost of components has also changed. If you place an order as of now, your board will be secured and placed in the backorder queue to be fulfilled as soon they are available. This will be roughly 2 weeks according to the factory.