Hi, Tara! I'm a stay-at-home mom, for the most part, and Mystery Shopping works great for me. I actually work part-time two days a week at a retail "day job" and schedule a lot of shops on those days because I have a babysitter already lined up. I've also learned which jobs I can take kids along (I have a daughter who's 4 and a son due in March), which really helps. She loves to come with me and be my "helper." Also, there are quite a few phone call/web inquiry shops available that can be done completely from home. They don't pay as well, but if you factor in the daycare savings and the ease of staying in the house, they can be quite valuable.
Good luck and keep us posted on how things are going for you!