If you have to pay for it, it's not legitimate.
And as a side note, I want to say something. You say you're a SAHM. Can you do all the work of a virtual assistant while your children are there? You'll need to be able to do things like answering phones (without crying in the background, it's a professional environment) and all the other work that comes along with a normal assistant job. It's something I seem to see a lot of people overlooking. Unless your kids are school aged, I'd say you'd still actually need childcare for them even if your job is virtual. Just my two cents.
Also wanted to add, a lot of the people who I've seen start successful home businesses did just that, started the business on their own. Jobs in that area are very scarce and very competitive because who doesn't want to work from home? I've seen moms start all sort of businesses though from organic produce delivery to childcare to actual office services and baby gyms.