Ya' Know?
Get that chip off of your shoulder!
Why do you need OS X 10.9 Mavericks, so bad?
Does the Audio and video software you want to use or already own run on OS X 10.8 Mountain Lion instead of OS X 10.9 Mavericks?
I am still using older versions of iMovie, Logic Express and Final Cut Express on OS X 10.8 Mountain Lion.
These all worked in 10.9 Mavericks, but iMovie '06 HD and Final Cut Express weren't as stable on OS X 10.9 Mavericks.
They all run fine on 10.8 Mountain Lion.
I do some "semi-professional" video work still using these older programs on a newer version of OS X.
OS X 10.8 is only $20 U.S.D...
What is the problem with using 10.8?
What is all your rant and raving really about here.
I used to be a full time professional designer and illustrator and I work with an iMac much newer than yours to do proefessional level work!
Apple caters to more potential consumer level Mac buyers, now, but they still produce Macs that you can get options that cater toward more of the professional, working user, too!
I don't feel like Apple has abandoned me, at all!
Another thing that was already mentioned,
If you are a professional as you claim to be why oh why on planet Earth would you purchase a nearly 9 year old MacBook Pro?
You could've purchase any more recent Mac with a LOT more CPU, GPU and RAM power/resources for doing professional audio/video work than something 9 years old.
Anything from late 2009 on would have much more computing power and resources needed for the professional level work you do.
Why would you purchase a Mac that would kinda of cripple your professional work efforts and work flow?