Robotic Plateform Development

I am looking for an experienced robotics engineer to design and build a small robotics platform that can accomplish the following goals

The goal of the structure of the robot will be
1. 12-15 inches shoulder width, 40-inch height extendable to 60 inches
2. Be able to lift 50 lbs(22.68 kilograms) while climbing a standard flight of stairs.
3. Be able to manipulate small objects and work tools such as vacuum cleaners, sinks, and sponges.
4. Be able to sense and see the critical things required to avoid injuring living creatures or themselves while manipulating small objects or climbing stairs while carrying 50lbs.
5. Be able to accomplish everything mentioned for $500 or less when manufactured

I would like to do this in Four phases
1. Rough design with calculations of lifting capacity, speed, material, and electrical components to be used with specs.
2. Review the process with other engineers to evaluate the feasibility of the design. (First payout after meets critique)
3. Creation of a prototype, tested and shown to meet requirements.( Second payout when video confirmation is received of completion of requirements)
4. shipping and troubleshooting any complications in shipping to ensure the arriving prototype can still meet requirements and can be used to meet requirements.(the final and largest percentage of payout for completed platform received tested and troubleshooting if needed)

to be selected for this project you will need to show a complete understanding of the project scope and your ability to achieve said goal. No blanket proposals will be acknowledged. Request for more information will be ignored unless questions are directly based of project scope to clarify scope to ensure a better understanding of the requirements