Have Photography Bundle But Want Another Application not included

I need some advice on how I should go about my problem. I currently have the Adobe Photography bundle which costs $9.99 per month. As an aspiring photographer, this bundle has been extremely helpful and well-suited to my needs. However, I have been wanting to explore and play around more with Adobe. I am particularly interested in Illustrator as I want to delve deeper into graphic design. As such, I began looking into the app and saw that it was worth $19.99 per month, more than the bundle cost. Is it worth buying this one application for $19.99 per month? I am not so sure. Moreover, I saw that the Creative Cloud bundle is worth also $20 per month, so if I wanted Illustrator, would that be the better bargain? (Sidenote: if I get the Creative Cloud Bundle has everything, so how would that affect the applications I already own? I do not want to purchase the apps again, if possible)