You can use Easy Buy with a Wanted List. Probably most buyers do. I don’t buy this way. I want to buy from the least amount of stores. Easy Buy looks at the best pricing and shipping. I would pay a few cents more for a piece if I could get it from one store. This is how I buy pieces
From the top of the screen I go to the Wanted List.
Going to this screen I will click on the Wanted List I want to buy from instead of clicking on Easy Buy
I will select one of the more unique items from the list. I am going to choose Electric Guitar. If you click on the item number 17356pb04, it will take you to the catalog page for the piece.
Under Price Guide Info there is a list of colors. This one only has one color.
Under Current Items for Sale I can look for the quantity I am look for under the New and Used columns. The red squares means the seller doesn’t ship to me. The “~” before the price means that price has been converted to USD. The seller is located in a different country. If I click on a green square it will take you to a store. From here you can’t see what store it is.
You will go to the listing for the guitar. If you click on Wanted List it will show what pieces this store has on your wanted list. This store only has 4 out of 10 items from the list. Now I can either add the items to the cart or I can go back and try another store.
If you are trying to build a set from scratch Easy Buy would be easier. I am usually looking for a few, select pieces at a time and usually in large quantities. This way works for me for how I buy on Bricklink. Either way, once the pieces are in the cart you can proceed to Checkout.