bleeding heart bakery makes GREAT cakes and they have vegan, Swirlz and most of the cupcake places make vegan cupcakes, Whole Foods, Fruitful Yield, and main line stores such as Jewel and Meijers carry vegan/gluten/soy/dairy free cake mixes.
a good website to chk out is : http://www.godairyfree.org/
Really, think of it this way mommies, Cow Milk is for baby cows. Not humans. Humans are the only ones who drink another mammals milk product on a regular basis. our bodies are only meant to digest milk until weaning, after the age of 2 our bodies no longer product the enzyme, lactase, to digest the molecules that make up milk. Goat milk is easier on digestion as they molecules are so miniscule compared to cow milk. Anyhow, there are so MANY delicious healthier replacements for dairy. Watch out for Casein though, a component in some dairy free cheese and other products which can also be an allergen especially in small children. Earth Balance makes an excellent soy free, dairy free spread, which tastes just like butter and is what Swirlz Cupcakes bakery uses to make their frosting for their Vegan cupcakes.
Alternatives to milk for drinking are soy, rice, oat milk, hemp milk, coconut milk (made by Turtle Mountain/So Delicious brand--not in a can, it's in the refrigerator section of most Jewel stores and Whole Foods), vanilla almond milk is my favorite for smoothies and cereal, I get the unsweetened kind. There are tons of options, just need to shop different. Meijer's has a great gluten/allergy free section and Enjoy Life brands are local to our area and have tons of allergy free products. They now own Ian's, who makes frozen chicken fingers, etc which are also gluten/dairy/soy etc free. You just have to read labels. one of the major cake mix companies also makes an allergy free cake mix, and so does Cherrybrook Valley or something like that. Meijer's carries both. Good luck, send me a message if you have any questions I can answer, I've been doing this for years as my husband has many food allergies and intolerances (not the same thing, but similar)