You could also list fashion awards she won (like being in Hall of Fame for winning 3 times Nail Queen, and Hall of Fame for winning 5 times Best Jeanist of the year), besides the many fashion pools (some held by Oricon) that she was on top
Besides, I don't really remember which article was it, maybe it was the same mizuki-7 posted (the first one), that an owner of a clothes store was saying in 2001 that if they stocked any clothes or accessories similar to anything that Ayu worn, those were guaranteed to sell out.
EDIT: yep, it's the same article mizuki-7 posted, just checked ^^