Take a look at membership plugins. The first look at even free membership plugins can be overwhelming. From your description, the functionality you need is a redirect to a member page on sign in and the ability to protect the private pages.
I use S2member. The free version will do what you want but it has a learning curve. You may want to look for a simpler membership plugin. And there is always jobs.WordPress.net if you can fit a paid job into your budget.