How do you go about figuring out how much to pay for full, part or contract work?

I started in the IM and Web tech game super late but I put the work in and have learned loads over the past year or so.

The other day I came up with an idea that would involve linux administration and intensive understanding of PHP for larger scale application. These are two areas that i’ve always shyed away from as i’ve never particularly needed them, but now I need both and ideally at scale too.

I’ve worked with PHP for testing what’s involved and although i’m sure I could learn the ropes I feel it will take too much time to use it in an OOP style that is needed and I hate the idea of having to do so. I think I would rather hire someone to do the heavy lifting involved here.l for a change.

But as it’s my first large scale commercial (SaaS) venture, although I imagine i’d be able to recognise good work when I see it, I just don’t have the first clue how to assess how much I should be paying someone for the work involved.

1. Skill level (measured in verifiable work experience)
2. Country (employee location)

That's how most companies do it.

Check whatever marketplace you feel comfortable dealing with freelancers there, and analyse what others are paying them, then go with average.