Would you like to be flexible? Are you not sure how much help you exactly need? Consulting on an hourly base is probleby the best way to go.
Outsourcing single and more analysis or some statistical programming will save you hours, days and weeks, why?
Consulting on an hourly base can be easily combined with small and large projects. You can easily set a weekly or monthly cap on the number of consulting hours so you can stay within your budget.