Check babies r us. It won't be as fancy as juicy couture, but they have some celebrity baby clothing lines. I wanna say it's by heidi klum, but not sure about that. Also google the honest company. It's jessica alba's diaper line and they are super cute. Not as expensive as I thought either. I'd also check online, just google search famous brands with the words "baby clothes". I'm not trying to be judgmental, but I hope your friend realizes how messy these clothes will get. Babies outgrow them fast, plus they poop, pee and spit up all over pretty much everything you own. If she's on a budget you might try to politely bring this up. There are lots of cute clothes in more affordable brands (like carters), that would be far more practical. She would get more for her money and they make a lot of mix and match stuff.
Best thing you can do is to search online for wholesalers and distributors. Shop around for prices and call them personally when possible. If your planning on selling name brand apparel, there might be some obstacles.
Many companies who's products are "high end brands" have strict policies as to whom and where they are distributing there products to. They are many marketing reasons why they follow these policies. One of them is so they don't have there high end products being sold at small "Ghetto" stores for a lot less than upscale retail stores. This would diminish the brand. Think about it.
A biz that you might consider if you want to sell name brand is to start a "out of season" / "defective" outlet store. You would be able to buy truck loads of high end named brand clothes from a broker. Similar to Burlington Coat Factory. There is a store like this close to where I live and its always busy.
I dont know where they get there clothes from, but I do know that this is the only store the owners have.
Good Luck to you