The servos are certainly where you can spend most money when building a robot for research. I tried building small research robots with small servos ($25 each), see results at the end of this video: https://m.youtube.com/watch?v=q8jgu-EtCFc

The total cost for one robot was well below 1k. The servos are $25 each (Turnigy 306G if remember correctly), all connecting parts are 3d printed, the electronics and batteries are about $50, and you could add a raspberry pi for $50. So in total <$500, depending on number of DOFs.

Of course, these servos don't have the same torque as Dynamixles, for example. But they are lighter!

Do you have any videos of the actual robots or just the simulation?

thanks, that's what I was looking for. Do you find the 306Gs work reliably and the cables don't get messed up in routine research work?

I am trying to build a suspended robot for about $1000 as an open source project:

http://fae-bot.org/

Unfortunately at that price it comes without a manipulator, but I have bought (very) cheap arms and will experiment with them soon.