I started with one product and have grown to 150+ products across 9 brands. Heavily focused on e-commerce and automation. In addition to launching our own brands, we acquire other e-commerce companies and scale them to the next level by focusing on digital marketing (Adwords/FB/Insta/email) and business automation. I love to teach people how to stop working IN their business and start working ON their business. I can help with product sourcing, team building, and digital marketing questions for those wanting to create branded products (private label and contract manufacturing). I have experience outsourced fulfillment, customer service, production, marketing, and more. I also can help you with a deep dive into your financial statements to pull out metrics you should be monitoring to increase your profits and squeeze more cash out of your existing business.
If you're looking to build a service like Xero that imports users bank transactions and balances, you've got a few options.
Xero uses Yodlee on the back end to power their bank feeds. As I understand it, it's rather old school and often errors out, but supports a huge range of banks through scrapers, private APIs, and all kinds of proprietary technology.
You can also check out Plaid - you can think of them as the modern version of Yodlee. They support a more limited number of banks, but have an excellent API and SDK, and I believe are much more affordably priced than Yodlee.
My best guess is that you'd get it close to wholesale price, which is anywhere between 30% and 50% off retail price in the electronics industry.
You'll need a sales tax license number to prove you're a business rather than an individual.
Pricing requirements will depend on the manufacturer. Some will have a "MAP Policy", which stands for Minimum Advertised Price, that dictates the price you advertise on your website. Note that "advertise" and "sell for" are not the same thing - that's why you see some sites that say "add to cart to see the price" - they're circumventing a MAP policy. Unless they make you sign a MAP Policy though, you should be free to advertise and sell at whatever price you want.
Honestly, you're going to have a hard time getting any company to do a run this small. The main reason is that setup costs to configure and turn on their machines are going to be so high that your unit cost per box will be $10-$20.
Custom cardboard doesn't really start to make sense until 500-1000 units, and even then the economies of scale don't kick in until ~5000 or so.
Your best bet would be to think about stickers. With 2-4 well placed and full color stickers, you can make a stock brown (or white) cardboard box look pretty custom. Checkout Uline to see what boxes they offer, and try to think about what stickers you could add to make them your own.