cost of purchase

Hello. Small business question (just starting out). 

 

I just started my small business--What if I bought many items on sale (candle vessels) that go into making my product--but these items won't be on sale in the future so I need to save a higher amount from sales in order to repurchase the items in the future (in order to make my products again). Will I be taxed on income I made from the sale that is extra than it would have been if I didn't buy cost of purchase on sale? is there a way to account for this as my net income isn't higher since I will be saving the amount I need to purchase the vessels at the higher price next time I need to purchase inventory? I feel so lost! I would appreciate any helpful answers 🙂 Thanks in advance!