hi :)
certain gyms will allow you to purchse classes only for a lesser rate. most also offer childcare -- at least during 'peak' hours. (morning & early evening).
where are you located? that would make a big difference.
in kettering, the rec center has a gym, as well as classes. i haven't been there in ages, but used to take aerobics for only a few dollars.
the ymca's of the area usually want you to join, but i think you might be able to do classes only. the nice thing about the ymca is you don't have to have a contract (but you do have to pay a joiners fee). also, they will consider your income when deciding your monthly fees.
one of the gyms i go to is called 'better bodies', but it's all the way in fairborn (i have no idea where you live). better bodies will let you purchase classes only & they have them in the morning 6 days a week, and in the evening 5 days a week. they offer free childcare too. i actually take a zumba class there & the instructor was trained by the owners of the studio that was mentioned in an earlier post on this thread.
i myself had a terrible experience with premier lady fitness, but that's just me. a lot of people really like it there. plus there's no men!! :)