Tobster86:
I'd be more than happy to use a 5V switching regulator to step 24V all the way down to 5V; probably something like this http://uk.rs-online.com/web/p/buck-converters/0398477/.
nb. That device needs external inductors, diodes, etc. You can't just connect it up on its own like an LM7805.
(The boards I linked to on eBay are basically one of those with the needed external components...)