Hi,
Rather than using an app, I think the best way to implement this is to convert your pdf into an iBook.
That gives you all the features you need (table of contents, page navigation, interaction), and allows reading using the iBooks app on iPad, iPhone and OS X.
You can see some examples of my app development work, and client reviews of my completed projects, on my Freelancer profile page. Most of my iBooks have been developed for clients who don't use Freelancer, but there is an example on page two of my "Completed Work", called "Hypo needles ipad presentation". After discussion, the client decided to use an iBook rather than an app, and the result turned out very well. This was a fairly substantial project (£750 budget).
You don't say how complex or large your pdf ebook is, but a reasonably straightforward book would be achievable on a $250 budget. I'd like to see your ebook before going ahead, and if you'd like to respond to this message, we could discuss the options.
Best Regards,
- Rob Dixon.