Joomla! 2.5.6 Virtuemart 2.0.8 Conditional custom fields by jenlusl

I have virtuemart 2.0.8 set up and almost ready to use, I need to be able to select a custom field (already made) and for the selection to change the results of another custom field (already made). … (Budget: £20-£250 GBP, Jobs: PHP)