I think there is some truth In that, I've seen a few fake shirts in my time, in some instances I'm certain the fabrics are the same, possibly made by the same people, just the badges that remain sacrosanct. As for the cost, right now they're £30 because the sellers know the real one isn't...
So long as clubs charge so much for footie shirts, and this year sees another increase in the prices of the Albions kits, the fakers will continue. The one I bought seems perfectly well made, the fabrics are pretty much indistinguishable from the real thing, the attention to detail is...
They are fake of course, I bought one out of curiosity, £29, it's pretty impressive for a copy, the only real visual clue is the Seagulls badge. I doubt many would spot it as a fake without close up scrutiny