Thank you for taking in the little lost budgie.
I agree with Cody regarding the risk of illness and/or infection.
Check with various vets in the area as well as Animal Shelters to see if anyone has reported a missing budgie. Making flyers, posting on Craigslist, etc. would be helpful.
Have you been able to locate the source of the blood on the budgie's foot?
Are you certain the budgie isn't still bleeding?
If you are unable to find the owner, is it your intention to keep this little budgie?
When you print up flyers, I would not include a picture of the bird nor an extensive description.
Simply indicate a Budgie has been found, the location where it was located and how to contact you.
Ask anyone who responds to the flyer about a "Found Budgie" to carefully describe the bird to you. This will help ensure you don't get someone who simply is trying to get a "free bird".