well i have some questions before answering.
Are you paying for finished project?
Half upfront, half when done?
pay by mile stone?
what is your target platform?
besides the platforming aspects, what other features are you planning on? and including what features are you thinking. Some features are easier to add then others. Also polish is different than core developement. How much polish is planned for the game?
you mention your on a budget, but is that a low budget, high budget, AAA budget :D