An original Battle Circuit is going to be hard to find/expensive, and it won't come in blue (aka wasn't released in USA).
Why not just convert another common/cheap game into a Battle Circuit?
We have the information for key writing now, you don't even have to use the decrypted (Phoenix) set.
*Update* My bad, as @zero238 pointed out the Euro/World release of BC WAS blue (still was never released in USA tho).
Yeah, Blue Euro board will be a pain to locate. Not sure why these are so scarce. I landed a Green one a couple years ago, and I think I saw a Grey one on ebay last year, but since then I don't think I've seen any. I'll keep an eye out for you, though.