What are some of the accurate and natural-sounding column name for this?

Question

I am creating a table that shows amount of units of whatever that’s being sold in the shop and the corresponding price per unit. The idea is that there is an incentive to buy in bulk – the more the seller can sell you the cheaper they are happier to sell it to you for:

range of the number of items purchased	price per unit
1-5	5 dollars
6-10	4 dollars
11-20	3 dollars

So if the number of items you are buying is equal or bigger than 1 and equal or less than 5 then the price per unit is 5 dollars.

My question:

1. is "range of the number of items purchased" an accurate and natural-sounding column name?
2. any suggestions about any parts of the table?

Answer 1

I add to what @randomhead has suggested. Other than number of items purchased, we could consider purchase quantity.