In scopes of 500$ I can update Flex version from 3.5 up to 4.16, fix some issues and build IPA and APK. New design, new appications and migrating from MX to Spark will be separate work.
Relevant Skills and Experience
I'm 6+ year enerprise Flash/Flex developer both games and business apps.
Proposed Milestones
$200 USD - Update FlexSDK veriosn in project from 3.5 to 4.16 and build swf
$150 USD - do some testing and/or went through your issues list and fix criticals
$150 USD - build IPA and APK files with your certificates, check on iPad and Android phone
Additional Services Offered
$200 USD - migrate UI from MX elements to Spark
$500 USD - do refactoring using IoC MVC framework (Robotlegs or mvcExpress)
$250 USD - redesing and optimize with profiler for tablets and phones
$50 USD - update your PlayMarket and AppStore settings and publish apps with screenshots and etc
Do you have previos developer I need to contact with? Or just source?