I'm willing to investigate your problems. Although I don't know the CakePHP and I'd take this job as an opportunity to learn it, I think it would be profitable to let me handle at least the simple bugs - as I can offer attractive prices - and then, perhaps, to assign the harder ones to someone else.
My current bid is a pure guess - I will adjust it when I know the details, but, generally, you should expect a cost between 3 to 5 USD per hour.