And she got her wish; she has seven grandkids. But Costin isn't like most grandmas.
For The Early Show's Young at Heart series, correspondent Melinda Murphy found out Costin started her own business just last year.
To customers who call, she answers, "Grandma's Handyman Service. This is Grandma speaking."
Her company does home repairs.
"We do from major remodeling of kitchens and bathrooms all the way down to turning on swamp coolers, replacing washers and faucets," she says. "I like to do wood restoration myself."
She has six employees, including her husband, Theron Costin, who goes by the name "TC."
Asked if it is strange to work with him, she just makes funny noises. So what does TC think of his wife starting her own business? Laughing he answers, "Got her out of my hair."
The truth is, Yvonne Costin has been working around the house for years, repairing the family's front doors and other odd jobs.
"I'm from the old school: Use it up; wear it out; make it do; or do without," she says.
Of course, it's not always easy working for a grandma.
Costin started the business at the ripe old age of 64, after she had retired from a career as a secretary.
"I started to look at my past," she says, "think about all the things that you could've done, should've done, would've done. And it was kind of depressing. And then, when I got together with Michael, we started looking forward.
Michael Giltner is her business partner, a man with years of construction experience. They met when he was building a deck for her home.
He says, "She's has an unlimited amount of knowledge that's just sitting there, harnessed. I can learn so much from her, just as much as she's learning from me."
One of those things is how to treat customers. Yvonne believes in good work for a fair price. And she is especially concerned with the elderly.
She says, "As I became a senior, I noticed I would get these phone calls. And you know that somebody's trying to take you for a ride. You just know it. And I thought, 'Well, let's do our part and help them.'"
Customer Sandra Arkin says, "It's a company of grandmas by grandmas and for grandmas. And I'm a grandma myself. So therefore it makes sense. They do a wonderful job. They really know what they're talking about, and they're very professional."
And younger customers, like Walker McDonald, couldn't agree more. He says, "We trust them in our house, which is a big deal. And we trust their craftmanship."
Yvonne Costin says she's not getting rich doing this, but working is a lot more fun than being a regular grandma.
"I didn't know I was bored," she says. "I thought I had plenty to do. You could do things for yourself all day and not feel the satisfaction that you feel when you're doing it for somebody else."
So would she ever retire?
"No I won't," she says,"You can't. I know if I retire, then I'll be thinking about the past rather than the future."
Grandma's Handyman Service has already helped 100 customers during its short existence and Yvonne Costin and Michael Giltner have plans to take the company national.