Transfer Promo Details:
Delta charges 1 cent per mile to transfer miles between SkyMiles accounts and a $30 transaction fee. The yearly maximum number of miles you can transfer out of your account is 150,000 and the maximum to receive in a year is 300,000 (both of those are excluding bonuses). You can transfer to up to four different Skymiles accounts up to 30,000 miles each per transaction. To maximize this, let's pretend that you have 4 people in your family, you could transfer each 15,000 miles (60,000 total) and they'd each end up with 30,000 (120,000 total) thanks to the bonus. Cost: $630 since you only pay one transaction fee to transfer to up to four accounts.
Then each of them would transfer 30,000 back to you (you'd receive 60,000 from each, so 240,000 total) at $330 x 4 = $1,320. In this case you'd have to pay the $30 transaction fee for each of the four transfers since there are four different SkyMiles accounts. If you don't mind the miles being split up in different accounts, you could save on transaction fees, but for the sake of trying to maximize this promotion back into your own SkyMiles account, this is the easiest scenario (though feel free to disagree if you have different ideas).
FYI in order to transfer SkyMiles, both accounts have to be open for at least 10 days, so if you don't have one you can create one here for free. You will also need to generate at least 1 mile in the account to make it active before your transfer, so you can do a number of things like transferring in 1,000 American Express points (which post instantly and there's currently a 30% rebate if you transfer at least 50,000). You could also sign up for Delta dining and make a dine and get the 1,000 mile New Member bonus. Dining miles usually take about 7-10 days to post, so I'd recommend doing this sooner than later.
Essentially you would have gone from 60,000 miles to 240,000 for $1,950. So, you generated 180,000 SkyMiles at 1.1 cents apiece - pretty good!
While SkyMiles can be hard to use, if you do enough research 240,000 SkyMiles can get two people to Africa (excluding South Africa) or Asia in business class. In fact the Africa awards are my favorite to book with my SkyMiles - last year I did Paris and Seychelles and this year Madrid/Barcelona and Mauritius - each trip was 120,000 SkyMiles and about $250 in taxes/fees each for all legs in business class. You can also use 150,000 SkyMiles to fly to Australia in business class - including on partner airline V Australia. Taxes are a bit steep at $550ish, but it's still a great value since those flights are easily $6,000+.
For tips on maximizing Delta miles, check out some of these posts:
How to Book a Delta SkyMiles Award
Maximizing Stopovers, Transfers and Open Jaw Ticketing on Delta Awards
10 Tips on Using Delta SkyMiles
(They also ran this promo in September - click here to see my original post on the deal.)
Buy Miles Promo Details:
The Buy Miles promo is much less lucrative and I don't really recommend it (buying US Airways miles is cheaper and they are generally easier to redeem).
Delta charges 3.5 cents per mile, plus a 7.5% tax and their yearly maximum on purchased miles is 60,000 (excluding any bonuses).
So if you purchase 60,000 miles at $2,257.50, you'll get a bonus of 45,000, so 105,000 total at 2.15 cents apiece. Better than normal, but still not a great deal - especially since you can create miles for half the price using the transfer method.
