If you're asking "is MEI RA1" actually a Panasonic media code, it is. MEI = Matsushita Electric Industrial = what is now Panasonic. And it is indeed one of the higher-speed disc models, the 6x variant. (4x is T02, 2x is T01).
If you're asking whether the discs are genuinely made by Panasonic, we can't tell from the info, but there's no reason to believe they would be fake. If you can read the codes on the inner part of a disc, we can doubly verify that they are indeed genuine, but i wouldn't worry.
Not sure why the product code doesn't come up on an internet search; it may be that Panasonic no longer sells 25 disc spindles, though at one time they did. (Most search results I get now are for 10, 30, and 50 disc spindles, with product codes similar to the one you mention -- LM-BR25...).
And the actually cost of the discs depends. They might be more expensive in some stores but not others. But they are theoretically just as good as Panasonic's other media.