You don't have to have status to buy a gift card. There are a lot of ways to extend the expiration date of your miles. You can buy 1000 miles, though that's an expensive way to do it.

Or, do this: Log on to Delta.com. Click on "SkyMiles" then "Ways to Get Miles" then "Dining Retail and other Partners." There you'll find many ways to get miles. (FTD miles usually post within a week; Netflix miles never seem to post.) Or click on "SkyMiles Shopping" and find an online vendor (e.g. iTunes, Eddie Bauer, Lands End, Target). One purchase from any of the vendors listed will extend your SkyMiles expiration date, even a 99 cent purchase from iTunes.

You need to buy something soon though because sometimes it takes 8 weeks for the miles to post. I've had the best luck with iTunes, FTD and Staples.