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.