No not at all. I was interested in a specific model and I think the salesperson could tell that I was prepared to buy it if they had it in stock. So the additional discount was offered by them as an incentive to buy the alternative. I didn't bring it up. But she said it was a one-time deal. You can play by ear and see if it'd work for you.

BTW, the VAT refund stamp desk before passport control at FRA Term 1 can be overrun by a busload of tourists from tour groups so be prepared to wait. My experience was on a departure Sunday morning. You need to use it if you are checking in the item. There is supposedly a separate VAT refund desk for carry-on after passport control. However the Term 2 one was much shorter.