Try to consider that there are several metrics to secondary markets:
Obviously, how much you're paying per unit
The condition of the units -- new/perfect, inspected returns, refurbished, incomplete/damaged etc.
How many you have to purchase to get the wholesale price
How rapidly are you going to be able to realistically expect to move the product?
Can you get more after these are sold out?
If you were to prioritise these five variables on a scale of 1 to 10, you'd naturally weight most of them close to 10. But in reality, you only have 25-30 "points" to spread around out of an ideal value of 50. The lower the price, the greater concessions you're likely to have to make on quality, MOQ and duplicability. Get the MOQ down to 1 (or to 0 in the case of dropshipping) and you're most likely going to sacrifice cost and quality. Get the duplicability perfect -- ie. some hot selling product for which you have a reliable, bottomless source -- and you'll probably have to make concessions on price, quality and MOQ.
It's just an unfortunate fact of life. Any "perfect 10 supplier" has no reason in the universe to sell to you at wholesale, since it could make massively more selling directly to the public.
This is not meant to be discouraging (my standard disclaimer when I post stuff like this!) I'm just saying that you have to get a feel for the markets for the products you're trying to sell. Especially when selling on eBay, where virtually everything sells for well under retail and many volume sellers are doing the same thing that the big retailers do -- sell next to zero markup in order to gain repeat customers and make their profits on volume.
"Failure is not when you fall down. Failure is when you don't get back up."