I've been selling on the internet now for close to 20 years. I'm low-volume, low-overhead, and everything is made to order. So I know all of my fixed costs, material costs, etc. In all but a very, very limited number of instances, I do not distribute to resellers.

Because I long ago crunched the numbers-- my profit margin has historically hovered around 67%. Some items a little lower, some higher. Shipping is usually one of my biggest costs-- packaging, labels, tape, and of course the shipping charge itself-- I have some $35 items where shipping accounts for 20% of the total.

The only flex I'm willing to make would be to reduce the per-unit cost to a reseller, so long as that discount falls within the overhead; for instance, if a $50 item costs $8 to ship and I can sell a lot of ten to a reseller, I would have about $70 worth of wiggle room in pricing the lot, not having to pay to ship individual units to individual customers. But resellers traditionally want to carry a margin around 50%, so I'd have to sell them a lot at a per-unit price that would likely drop below my per-unit profit selling individually. I'm not going to cut my own margin so a middleman can scrape a profit.

I found that the number had to get up to around 20 units-- at that point, I could knock 12-15% off of the net price and still make money, just in the savings from the packaging/shipping. But most of the sellers I've been in contact with want a grab-bag assortment, and not 20 of one thing. It's just easier on me all around to sell direct to the customer. Now if I were moving hundreds of items a month, sure. But I work in a small niche.