I want to get saline implants. I'm a saggy 38D wanna go to perky DD.

Having not seen you, I would still guess that you most likely need a breast augmentation AND a breast lift (mastopexy). The augmentation will increase your cup size, namely going from the D to DD-cup. The mastopexy will address the saggy appearance. 
These procedures can and are often done at the same time. Combining the two is helpful from a cost reduction and total recovery time standpoint. 
I would advise meeting with a board certified plastic surgeon so that you can discuss your goals. Having a physical exam will be most helpful for the surgeon to determine optimal implant size and type of lift, if any, that is indicated. 
Best of luck!

Thank you for your question. Without photos it is difficult to give feedback, however a patient who presents with "saggy" breasts are typically candidates for a mastopexy in conjunction with implants for added fullness in the upper pole. I recommend discussing these options with your board certified plastic surgeon, who can individualize your treatment plan.