No, you're right, it's "Thanks but No Thanks" and smile politely...
'specially if they're offering their services, which it is what is sounds like. Although that's what friends are for?
I cut my own hair and mow my own lawn. If you really are selling your house, you could move to a larger town where everyone doesn't know your every move?
Be ever so careful though, to not say: "I can't afford it this month", which would ordinarily be a great excuse. They might offer to cut your hair for free. Don't go there, it's a seriously difficult situation.
I'd suggest that if your friend is a hairdresser, you make sure he or she knows that you're happy with your current stylist. If he or she provides a housecleaning service, that's even worse, there's no way you want a "friend" to do that for you.
But think about it the other way: I have friends and neighbours who work as builders/decorators and chefs and fashion designers and I wish I could afford to pay for their services. Instead I just feel fortunate to know them..
Luckily everyone in my life is brilliant at their job, that's one of the reasons why they are, and remain, my friends.
xL