We went through the same thing at the same age. It is very frustrating! I hear you, OP, about not wanting to feel manipulated. DH and I went round and round about that one. It is just a phase, though--she's not old enough to manipulate you, she actually is scared when you leave. I couldn't even walk by a doorway where he was without massive crying! But we negotiated it, and I was able to respond without feeling the manipulation.
Here's some strategies that worked for us:
1. Routine, routine, routine! As a WOHM, he had to leave me at daycare. This was actually never a big deal, b/c he came to trust his caregiver and went to her just fine. He loves to eat, and so our routine was that when I dropped him off at daycare I put him in the highchair, and we timed it so that he immediately had his breakfast. By the time that was done, he was happy and on to his day.
2. The crying usually stops shortly after you leave, so if you have to go--go! With DS, within 5 minutes after I left, (at most) he was fine and playing.
3. Ritualize goodbye. And make it quick! DS would start crying as soon as I started putting on shoes or finding keys or packing a bag. I waved goodbye, gave a kiss and left. The longer the goodbye-time lasted, the more anxiety he had.
4. Try not to "pop in"--every goodbye was traumatic, but once I left it was fine. So I didn't pop in to check on him, or even walk by a doorway where he was. It killed me--I loved going to see him at daycare midday--but it was better for him, so I abstained. More than once when I forgot something in the rush to leave the house quickly (b/c he started screaming at the sight of shoes), I called DH to bring it out to me in the driveway!
For us, it finally began to ease when he got the independence of crawling. Unfortunately, that didn't happen until 11.5 mos! Good luck, and this too shall pass.