Gift cards are a sure bet to make sure you don't repeat an item they have.
But if your in the mode to take a chance here are some other ideas:
Kayaking street clothing
IE t-shirts, hats, sweatshirt - all can be purchased from selected manufacturers websites or any local paddling shop.
For me I can't get enough different types of base layer options, long sleeve, short sleeve, pants, shorts, socks, etc. I love to have options for whatever the temp may be. NRS has a good description and selection of base layers.
If all else fails, I can never have enough Nalgene water bottles. They come in all shapes, sizes, and colors.