Yes proceed with caution. You may want to buy it from Roland. But with Roland I don't think they will give you any warranty if the board is not installed by a certified Roland tech. At the time DigiPrint had some pretty good discounts so it was quite cheap compared to dealers. I have bought things from China (not sign related) from AliExpress. They SAY they offer similar protections like Amazon or eBay, but the absolutely do not. They are not to be trusted in general. They are liars and thieves in my experience. They will post pictures that are not what they are sending. And that's OK with AliExpress. This is not Signs In China, I have no experience with them. But after AliExpress and things I have seen people post here and elsewhere I will deal with others first.
The instructions above are not completely correct for setting up the board after it's installed. I cannot remember how I did it now but I felt lucky that I figured it out. It's not really that difficult, but I was worried that doing the wrong thing would ruin the board.