There was a time when I would have bought one, or recommend that a family member buy one, but I've had the same ubiquiti APs for years and I'm happy. If you sell reliable hardware, it will take you many years to see repeat business.

If you start this business, bootstrap -- don't go into debt. If you have 100 units on your shelf, you'll sell them eventually. If you have a large loan, you'll have the bank breathing down your neck -- not worth it for the margins you're after.

At small scale you can economize on shipping by finding a small business that does a lot of receiving and intercepting their cartons and packing material. You can tell if the business's cartons are right for you by glancing at their corrugated cardboard dumpster, but if you ask, they may be happy to give you a load of boxes that they did not already break down.

Sell on eBay/Amazon, but also list your items directly on a website you control where you can bypass their fees. Perhaps the price is the same, but your site can be more profitable. Amazon may de-list you for offering a direct price that's lower than you list for on their site -- but you may be able to bypass this with a coupon code.

If you get good at shipping reflashed OpenWRT routers you will probably not be netting six figures. But by developing the skills of effective marketing and fulfillment, you may find a complementary product that is even more profitable at a similar volume to a similar customer base. The business you build selling routers can make another business idea take off even more quickly.