Recruitment contract for consultancy/market survey/questionnaire type of job

Please write a recruitment contract for a consultant type of role as described in the following:-
I need someone to work as a technical consultant or market surveyor for me on a project by project basis. Supervision is minimal. The consultant can work at his/her own convenience, carrying out survey/research/questionnaire on the market and industry, as long as the required report is submitted on time. Payment will only be made when I am happy with the end product. The consultant may also be asked to advise on the business operation or general strategies. Personal income tax calculation, reporting and payment will be the responsibility of the consultant him/herself.

A contract that specifies the type of report or survey required and the above payment structure is needed.