Pros and Cons of outsourcing project on a piecemeal basis

My apologies in advance for my lack of knowledge on this subject.


I am in the process of redesigning/building the user-interface of a PHP-based application, as HMTL5/CSS3 markup is my strong point.

So on the one hand I have a framework based (static) application - now on it's third iteration thanks to sketching/whiteboarding/user-testing amongst different age groups.

On the other hand I have a functioning PHP engine and a long list of jQuery scripts which need to be activated. And no experience in connecting the two.

In essence, I've all of the machine parts, and know how it should work (in my head), but haven't the time to put it all together.

I'm not strong on PHP, and thought it would be as simple as nesting the PHP functions inside the html markup and then renaming .html to .php

So onto my question:

With outsourcing being the current topic of conversation - would I just be asking for trouble if I outsourced this on a piecemeal basis (task by task), using a number of different developers for smaller tasks, or would I end up with a hacked together finished product?

I'm tempted to ask one individual or agency to handle it - but as it's more of a side-project, that 'might' generate some revenue (if productized correctly), it's difficult to find one quoting less than 2,000€ for their time.

So let me hear it: pros and cons. From the developer's point of view, I'm more interested in hearing.