If you have Access to the Dream World, you can grow the Berries and Send some to your game.. This will take most of a week from scratch to take down a several EVs. However it's also quite possible that by the time your Flower shop increased to Level 9 to get the EV Berries.
The Beauty Salon also removes EVs, but you need it to be level 7+.
http://serebii.net/black2white2/joinavenue.shtml Also you should check the shop listings on this page.. as you may discover you won't get the berries you want.
The best option for now is to talk to the Person on Route 5 every day, you may get Lucky.