All beginner controllers will suit your purpose just fine.
In no particular order:
Numark Mixtrack Pro (models I, II or III)
Pioneer DDJ-SB (models I or II)
Denon MC2000
Reloop Beatmix 2
They usually come with a Lite/Intro/LE version of the software that will only work with that particular controller (so be sure you get the software with the controller when you buy used) and will be feature-limited (for example no option to record your mixes or to change midi mappings).
All the big software (Serato, Traktor, Virtual DJ, RekordBox DJ, Mixvibes Cross and many others) have a built-in integration with iTunes. Even in the LE/Intro versions.
That should get you started easy enough.
I’d save up some money to buy the How To Digital DJ Fast course as it will kick start your understanding of how to work a controller in a proper way. Couple of weeks will have you fully up to speed (provided you do your homework and practice sessions 😀 ).
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