I decided to setup my home office to be a recording studio for podcasting. The room is fairly small and had a lot of reverb. I learned a lot along the way. Here is a detailed tutorial for how I built them.
Cost Breakdown for 8 Panels
Comes out to more like $200 with tax

Measurements
These are based on using plywood. If you’re using boards then they’ll be 1″ thick instead of 5/8″ and your back supports will be 4″ wide instead of 2″.

Resources
Fabric – (Silver) You don’t have to use this particular fabric but you do want to make sure that whatever you choose is lightweight and permeable.
Wood boards – 1″ x 4″ x 8′
Particle Boards – 5/8″ x 2′ x 4′
Insulation – Rockwool Safe n Sound 16″ – No hardware stores near me carried the 24″
I recommended 8 panels because that’s the smallest amount of rockwool you can get. If you just want 1-2 and don’t want to build the rest to resell, or if you’re on a limited budget. Here’s a video where you can make a simple, cheap one. It won’t be as effective but it will still help.