You're really sweet to think about this for your little sister, but please, think about another option...and, if I can be honest, I think 15 is too young as well, to be honest. I think it's cool that you're into fashion, and you obviously have great taste, but like others on here have wisely said...what else will there be to look forward to?
I'm a high school English teacher and I've been teaching for almost 10 years now. I see girls everyday in a very wealthy community carrying...backpacks. And less expensive purses. One girl carries a vintage
Coach from her mom that she adores, which is awesome, and another recently told me about a special Dooney and Burke her mom got her for Christmas, which she refuses to carry to high school because she doesn't want to ruin it.
I was in my 20s before I got my first Coach from a then-boyfriend, and for my 30th birthday, my mom (who instilled my love for bags, and Coach in particular) finally bought me a beautiful Coach bag and matching wallet. I know Coach is looked down on by many on this forum in general, but I love the brand. My point is, I was shocked at the gift. My 30th bday meant that much more to me because she got me something special THAT many years later.
My first Chanel woc was at 35, and my first Chanel PST was this year at 36. I know many don't wait that long or don't have to, and that's fine...I admire girls in their 20s on here who save hard to buy their first Chanel. I really do.
But 10? 15? Really? I'm just being honest. You can see it as rudeness, but I'm really not trying to be. What are you or your sister going to look forward to at even 18? 21? Life is marked by many special events - birthdays, graduations, etc - and if you already have everything you want, well, everything else is just anticlimactic. Run of the mill. In a word, boring.
Be a teenager! Encourage your sister to be a little kid! Save your cash to blow on going out in college and dressing up on weekends! When you're as old as me, you're going to look back and be happy you did. There's an expression on here that someone used: just because you can doesn't mean you should. My opinion might be unpopular, but I stand by it firmly. Be a kid. Don't rush. Life goes by too fast - trust me - and I'll never regret that I enjoyed being a kid first.