Freelance Pre Press Technician

I am looking for a company that can handle occasional prepress tasks when projects come up that we need help with. Tasks include taking client art and placing them on templates, preflighting art (check for fonts, rgb colors, separate colors), etc. The number of projects vary - sometimes there's 1-2 per week, sometimes there's more. I have been using a company that charges me $5 per task. Must be experienced in prepress and be available