http://www.torani.com

They have a wide variety of flavors. And simply go to their recipe
section and substitute the sugar free version for any sugar sweetened
item.

Sucralose aka splenda brand sweetener.

p.s. no corn starch.

Sugar free:

Almond Roca / Almond / Black Cherry / Brown Sugar Cinnamon
Caramel / Chocolate Chip Cookie / Chocolate Macadamia Nut
Chocolate / Cinnamon Vanilla / Hazelnut / Coconut
Coffee / English Toffee / French Vanilla / Gingerbread
Irish Cream / Lemon / Lime / Mango / Orange
Peach / Peanut Butter / Peppermint / Pumpkin Pie
Raspberry / Red Raspberry / S'Mores / Salted Caramel
Strawberry / Vanilla Bean / Vanilla / Watermelon
White Chocolate

There is a recipe section on the web site. I am curious what kind of
recipes can be thought up here.