I actually "Walk the Walk" and sell millions on Amazon every month. Don't waste your time on "bargain experts" or rah-rah courses. Talk to me when it comes to selling on Amazon: I own and operate Amazon and Ebay businesses that generate sales of 50MM+ annually. My success on Amazon is not through gimmicks, but implementation of time honored business principles twisted to fit Amazon and Ebay selling. My companies sell on Amazon using our own fulfillment, Fulfillment by Amazon (FBA) and we sell directly to Amazon. I am an expert on small technical issues (e.g. preparing a product to meet Fulfillment by Amazon specifications) to large strategic issues (determining which product are best sold to Amazon and which should remain being sold only through third party sellers). Additionally, I can give expert advice on manufacturing and sourcing. I directly manufacture as well as source (US and Overseas) a variety of products including Industrial, Medical, Grocery, Appliances, Beauty, Technology and Sporting Goods.
In 2017, I was the largest reseller of cryptocurrency wallets in the world including Ledger, Trezor, OpenDime, KeepKey and even my own manufactured products. From there I have spent years studying the markets and the future of cryptocurrencies. I can provide general insight, although I am not an investment adviser.
3x + inventory. Have sold my own in the past.
Amazon. Online stores are dying. They are moving toward boutique status whereas Amazon is what malls or strip-malls once were (before Amazon). If you don't know what you are doing don't try to learn it--lean on Amazon and focus on what you do well (product development, branding, etc.).
There are better ways to model this to protect yourself and align your goals, but 5%-10% off the top is common. This may seem low, but allows you to focus on throughput and not margin optimization while still allowing them to capture a large percent of the payment.
Amazon. Simplifies and eliminates all the things you don't want to be distracted by and let's you focus on your business. I recently helped a guy in Slovenia do essentially what you are trying to do.
Instead of money back guarantee offer a "110% of your money back" guarantee in the form of store credit. Use a third party to process returns and make the customers jump through hoops so you can play dumb and not be the bad guy. Add a non-refundable handling charge for returns. This is what small print is for.
Sell on Amazon. Avoid all the infrastructure and focus on your product and brand. Once you have scale and proven sales via Amazon, then you have something to stand on. UltimateDistribution.net could also help you with your cosmetics. They sell all the major brands.
I have experience in monetizing and selling companies both based on paid memberships to a forum and online courses. In both cases the value derives from you or your brand driving the purchase. So, you can't just create a course or private message board about, say, how to fix BMWs. There has to be a reason why they want to get the information from/through you. That's what will really drive the purpose. So, the passive income won't start out as passive, but can be once you have 1000 true fans (so to speak).
There are agencies that have relationships with major social media influencers with certainly some that are followed for their fashion sense and tips. Reach out to these agencies to target. You can target those influencers within your budget (obviously, the more "sway" the more expensive). Of course, they take in-kind compensation, so you may be able to "pay" the influencers compensation strictly with merchandise. It is not traditional "press," but is a lot more relevant.