Mass Effect Dlcs

Bring Down the Sky is free, as explained in the sticky thread: http://answers.ea.com/t5/Mass-Effect-1/MASS-EFFECT-BRING-DOWN-THE-SKY-for-free-NO-KEY-NEEDED/m-p/268840/highlight/true#M472

Pinnacle Station is no longer available separately, but it's part of the Trilogy edition. It's pretty bad, though. You can do without it.

I would like to know something though. The Origin store page for Mass Effect Trilogy says that it includes both ME1 DLCs. Now how's that possible if the DLCs are not aviable on Origin to purchase/download? 

The Bring Down the Sky DLC is available online outside of Origin. Pinnacle Station is not available in the store, but is still in the Origin system for those who bought it before they took it down. If the DLC is registered to your account, you can download it.