One of my two newly adopted budgies, Chance, actually got out of his previous home, wore himself out flying and ended up in an animal shelter before the Mickaboo bird rescue people got him.
I echo the sentiment of others here ... DON'T LET YOUR LITTLE GUYS LOOSE!
A budgie that has always known a life as a pet is not equipped in the least for life on its own outside.
If you're not going to keep them, contact Mickaboo
(if you're in California) or another bird rescue organization and let them find a new home for them.