Don't be contract-happy.
It will cost you an arm and a leg and you won't learn any PHP so you'll never be able to do it yourself.
I created such a site (www.ocprices.com which is currently moving house so it's not in the shape it should be in) and it took quite some time to get it all done (and I know PHP a lot better than you 🙂 )
Just do what you can and when you run into trouble, contact the forum (or me directly) and we'll help you as best we can.
And to of you offering your services: I hope you were joking. Too many PHP beginners have been conned to pay large sums of money because they couldn't estimate the size/cost of the project properly.