Hi Amour,

In order to treat your new studio right (congratulations ) you have to distinguish b/w sound proofing of external noises and leakage of sound from your studio to the outside and b/w acoustic treatment of the room and making it appropriate for mixing and auditioning your music in the studio.

:Sound proofing

One of the best way of treating windows and doors, finanfiacally and acoustically, is by filling them up with sea send, especially the doors. By increasing the total mass of the door you are increasing its performance.
Building a thick door made from plywood and filled with send you can increase its coeficient up to -35dB - -40dB (it depends mainly on the thickness of each side). This solution is relatively easy and cheap to build but there numerous others. Make sure though to install Neoprene in the small gaps b/w the door itself and the frame. It has to be air thight otherwise sound leakage would still accure., so no job done without Neoprene!

For the windows i would use sandbags as well. put the sandbags up against the windows and use the leftovers of plywood to frame it and close it. That should be sufficient enought, altough other alternatives exsists.

Acoustic Treatment:

Fortunatly, your room is big enought and can be treated adequetly.
I'm not going to write down 'How to' because there are countless ways to do it and it is also depends on your personal taste and how would you like your studio to be like but you have to bare in mind three crucial elements regarding to internal treatment:

- Reflection
-Absorption
-Diffusion
Each one should be treated seperatly and they are all important for best results.
Keeping the RT60 of the studio down to 0.3 Sec. should be your goal, by heavily absobing the low frequencies.
The rear side of the studio should be well covered with diffusors to maintain smoother overall sound and your position in the studio should be Refletion-Free-Zone(RFZ) with no early reflection down 30-35 milliseconds.

Your budget is fairly enought and you should be able to achieve great results.
However, some of the terms that i used may be new to you as well as the whole treatment so i would strongly recommend you to eighter READ A LOT before taking any action or even better, use the services of an Acoustician.
Making mistakes can cost you a lot of money and a lot of stress.
Good-Luck with everything and than again-Congratulation! ! !