Reddit mentions of Marvel's Guardians Of The Galaxy: Cosmic Mix Vol. 1 [Cassette]

The tapes are:

Peppermint Tea by Rest You Sleeping Giant

Cosmic Mix Vol.1, the Guardians of the Galaxy tv show soundtrack

This Means War by Volkor X

Also got a CD of the Badass Inc. EP and some stickers from Volkor as a surprise. Those were definitely not in the description on bandcamp lol

I'm basing it off this guide:
http://www.instructables.com/id/How-to-make-a-Mixtape-Awesome-Mix-Vol-1-from-Guard/?ALLSTEPS

The tapes are TDK CDing2 tapes. You'll want to go with a 60 minute probably, but they did make one that was 46 minutes long:
http://cdn.instructables.com/FXG/4KFN/I4IWVLUW/FXG4KFNI4IWVLUW.LARGE.jpg

The soundtrack with Spirit In The Sky included is 44 minutes and 36 seconds, so it would work perfectly if you can find them. Glancing around eBay they seem hard to find.

Cosmic Mix isn't based on anything, I don't think you even see it fully in the show. That image is some promotional stuff for the physical release I think and is different than the tape you get if you buy it new. Chances are if the tape was real it would also be on some form of TDK CDing2.

https://www.amazon.com/Marvels-Guardians-Galaxy-Cosmic-Cassette/dp/B016WGFPRS

If they were based on a real label it would probably be fairly hard to find. Cosmic Mix seems to just be the Awesome Mix label but purple instead of orange. You could re-create the labels in Photoshop/GIMP/Paint.net/Paint/Word/Anything from screen grabs of the movie if you wanted to. If not, there's a good PSD version of the label here (nearly 30MB!):
http://www.instructables.com/files/orig/FH1/2I24/I1MQ4BVP/FH12I24I1MQ4BVP.psd

To make it the Cosmic Mix, replace orange with purple.

These are meant to be printed on Avery 5444 labels. The alternative is to print onto 8.5" x 11" paper and attach the labels with a spray on adhesive. This is good if you want to weather it or whatnot.