Upgrade more than 10 installations from 5.2 5.3 to PHP 5.5

I have over than 10 (different) cms & other php 5.2 & 5.3 driven applications. Some had customizations to core as well. Can someone upgrade such amount of apps to php 5.5 by adding a special code to the core of each website? Much (popular) functions are just depreciated causing a lot of work to people like me. Do developers of php ever thought about that? Please advice with the best & cheapest way to proceed.