I think you left out:
Insurance costs (G/L, Worker's Comp, Business Auto)
Misc. stuff that you will need/might break during the course of the job.
My opinion-- the job is gonna cost you over $6000 and you only wanna add $3000 for you AND your partner?? Sounds way low to me, unless its a company you're REALLY trying to get your foot in the door with for some serious future revenue.