Library Prep

You can use kits from any manufacturer as long as they are specified for Illumina sequencers.  Illumina has many kits but there are third party kits available as well.  Some include the following:

NEB, Kapa/Roche, Lexogen, Claret Bioscience, Watchmaker Genomics, and many others.

Some of these companies have novel library prep methods that are faster, cheaper, or work with lower input amounts than traditional kits.