I've been sitting on this one for a while because I've been waiting for Bricklink inventories that still aren't done. But since some of these sets are getting marked down now, I went with Brickset to finish it up.
70348 Lance's Twin Jouster -- 216 for $19.99. Good parts in Black, Dark/Light Bley, Dark Blue, Trans-Orange, and White. It's also $0.09 per piece.
70358 Aaron's Stone Destroyer -- 251 for $24.99. Tons of parts in Dark/Light Bley, and plenty of Ball Joints.
70624 Vermillion Invader -- 313 Pieces for $29.99. Tons of useful pieces in Black, Light/Dark Bley, and Red. Plus some neat overmolded Minifig weapons.
70626 Dawn of Iron Doom -- 704 Pieces for $59.99. This one's outside of the normal price range I recommend but, it has a good PpP ratio and there are a lot of good pieces in the set.
70623 Destiny's Shadow -- 360 Pieces for $29.99. $0.08 Price per Piece and it has Olive Green Exo Force Arms!
70622 Desert Lightning -- 201 pieces for $19.99. Same as 70624, but you can find this one at less than retail in Target right now.
41307 Olivia's Creative Lab -- 91 Pieces for $9.99. A bunch of useful pieces in a range of colors. Thank you, Friends. This one would probably be really good for a parts draft.