Should I buy a domain name? Can a business use Google Apps Standard (free) Edition?

I think I’ve decided on a name for my new business, and Google Apps tells me that the domain name I like is available for $10. Should I go ahead and buy it through them? Also, they indicate that the standard edition is for non-professional organizations and that businesses should use the Premier ($50/yr) Edition. Is there any reason I shouldn’t use the free edition?