Hey there! I work up at the farmer's market every Saturday in order to get my name out there to do cakes and cupcakes. I sell cinnamon rolls, granola, and cookies to make it worth my while being up there. I usually bring a couple dozen cupcakes packaged by the 6 pack. There is a lady who buys a 6 pack of cupcakes most weeks. She has started to special order a pack of three strawberry lemonade and three cookies and cream (done with homemade Oreos.) Fine by me most weeks because those are my two most popular flavors and I've always had another order for a bday party or something for one flavor or the other, so it wasn't a problem. However, I'd like to bring other flavors up there and baking more flavors than I already bring is a huge time crunch when I have to provide her with three cupcakes of two flavors already. I don't want to turn her off since she buys from me each week, but I can't keep limiting my offerings. What should I tell her?

My mom (who is the worst cook in the world but a good businesswoman) thinks I should just freeze a batch of both her flavors and sell them week by week. I don't have the freezer space but if I did, would that even work? I told my mom it wouldn't because I'm dedicated to flavor and freshness has a lot to do with that, but has anyone frozen cake for more than a week?

I use to sell cupcakes at farmers markets as well.  I would tell her ahead of time you will be bringing new flavors that you are sure she will love just as much. 

I use to bring about 60-75 cupcakes to each market.  I was able to offer a bunch of different flavors using only a batch of vanilla and a batch of chocolate cake batter.  I would just separate the batter into different bowls to flavor if needed.  For example I could make red velvet by adding some cocoa powder and red dye to some of my vanilla batter (it already had buttermilk).  I could throw in some blueberries to another bowl of vanilla batter to make blueberry pancake cupcakes.  I would separate my batch of buttercream into bowls to flavor as well. 

Some of my cupcakes required special icing.  If I planned on smore cupcakes, which I used a 7 minute type frosting, I knew I would also have hostess cupcakes that day (which used the rest of the 7 min frosting).

You just have to plan and map it out.        
 

You can freeze your batter, bake as many as you need and freeze the rest of the batter for later. Here's a thread on freezing batter to check out.

http://cakecentral.com/t/740160/freezing-cake-batter

hth