Are there third party providers of Mechanical Turk psychology experiment services?
I would like to acknowledge the contributors to this post on stackoverflow.
Using Amazon MechanicalTurk if location != US?.

This question was posted a few years ago, but this answer is current.  

Houdini is a third party platform for MTurk, designed for non US users.

This question also leads to Houdini enabling non-US based businesses accessing mTurk.

At this stage, I have not found other providers, let me know if you'd like me to investigate further.

I have provided a link of crowdsourcing services similar to mTurk.