I would only go for her if u can need ALL the other spotlight units too.
Just a little story: When i started playing and discovered Princess Units i was very interested and once i saw Sybilla i fell in love with her on first sight. Since then i realy want her over pretty much every black (even though id take em all). BUT Chizuru a gold Samurai isnt realy a unit ud want or id want... i even already have her counterpart Kojuro. And u have to expect to get her more then once with a (not actual) 95% chance when going for a black. Garania is a nice plat unit i would take her anytime, Marnie though... right after waltz event isnt very much needed. For me personaly Marnie is the only plat unit i ever got from shrine summoning so its even less appealing to get her another time...
So as much as i would wish for it i wouldnt go for Sybilla. Now think about your Prioritys. And keep in mind: even if u spend 100 bucks its very possible that u get 0 blacks or a black that u didnt even want.