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. The song has somewhere between 30 and 50 tracks recorded that need mixing. I don't have a hard deadline for this. 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.