12 songs mixed (and mastered?)

Hey there! I have 12 album tracks that I have already arranged and mixed myself, however I think it could really use the polish from a pro like yourself. I was wondering: * What the cost would be per song / the whole album * If the files produced will need subsequent mastering separately? Many thanks! Sebastian

Additional info:
The tracks are cleaned, tuned, and and the song is ready to be mixed. I'm an indie artist. The song has somewhere between 10 and 30 tracks recorded that need mixing. I'm interested in working with a very experienced mixer. I'll need you to master it too if possible.