Just keep this in mind, the larger quanity you buy the cheaper it should be.
Normally 'buying in bulk', you could be buying as small as a pallet load or as large as a shipping container. The larger amount that you buy will normally lower the 'per unit' cost. For instant, if you bought a pallet load for $100. and it had 10 units on it, your cost 'per unit' would be $10. But if you bought a container for $1000. and it had 200 units in it, your cost 'per unit' would only be $5., thus allowing you to sell cheaper than your competition and/or increasing your profit ratio..