There's better stuff out now. The egg carton thing really didn't do much for the studios.... it looked cool for the times, but in reality, as a sound absorber, it didn't work nearly as well as the products we have today, and without the tacky egg cartons glued to the wall.
This site has some ready to go:
Acoustic treatment
Lots of folks also buy the parts and make their own.
home made More home made : Owens corning 703 rigid fiberglass 2x4 panels. A how to video.... I'd build the frames a bit stronger, I think he stapled them. I'd use some carpenters wood glue on the joints and wood screws as opposed to staples as the sole means to hold them together.
Youtube video These can be covered with any inexpensive fabric to your personal taste.
the important thing to remember is to get the high density insulation, not the stuff they sell at the hardware store for your attic.
Do a bit of research...
Since it is a home vs pro studio, you will find that doing simple things such as carpet in part or all of the room will go a long way toward taming the "brightness" of the room created by reflections. Hanging curtains, even on a wall with no windows will break up the solid flat sheetrock sound wave reflecting wall.
Another thing to consider: diffusion. Build a diffuser/art project to hang on a few walls as well.
Home made diffuser project Start out on the slim side. Don't go overboard and make a "dead space" with all sorts of room treatment. Add things as you find the need.
Another cool little Plug In to add to your studio is called ARC. It plugs into most things that can handle VST. Basically, it compensates for the room after it analyzes the room acoustically. I have is and use it because like most folks with home studios, this room does double and triple duty. So I'm limited as to what sound treatment I'm "permitted by the boss" to hang on her walls. My sound treatment is carpet and furniture as the diffusers. I think I get a fairly decent sound from this studio.
One day, I would love to have a room that I could build my studio in...and set it up as I want. I envy you guys with a basement that can be converted.....
About the egg looking stuff they are selling now.... If you want to add some for that retro-studio look, have at it. I'd opt to put some of that on the walls in a vocal booth... smaller space where quite often, DEAD SOUNDING SPACE is desired in there.
Have fun...and... take some pics.... before, during, and after. It's fun to follow a project such as a studio build....