Mixing / Master from stems

I'm curious what it would cost to mix my song from the stems up. I am in no way a sound engineer, more of an artist / singer / songwriter. I feel I write decent enough songs, but the final product still doesn't compete well enough with professional sound studio tracks.

Additional info:
The tracks are cleaned, tuned, and and the song is ready to be mixed. I don't have a hard deadline for this. The song has somewhere between 30 and 50 tracks recorded that need mixing. I'll need you to master it too if possible. I'm an indie artist. I'm looking to hire a top pro who's worked on hit songs, and have the budget for that.