What are your methods for cost effectively shopping for parts on BrickLink? How many parts do you shop for at once? How many do you try to get from a single seller? Are you ok with making small orders, paying lots in shipping and minimum order fees? What are your methods for using the site to optimize your orders?
My goal is to get the best total price for parts and shop from the fewest different sellers (to minimize shipping charges). I'm currently shopping for maybe 350 parts per set. Here is my method:
I manually optimize my orders since the Want List "Easy Buy" button doesn't do a great job. In a Want List, I use the "Buy All" button to view sellers with the most parts. I click "Select" on each of the best matches to see how much they'd charge, then scroll to the bottom of each list to see which parts are they charging a lot for. I will "Confirm Selection" for the shop with the best ratio of parts I need to total cost. Then repeat, finding other shops with good prices for the remaining parts that the previous shops didn't have.
This method reveals sellers with large inventories who charge a fortune for certain parts, though smaller sellers charge much less for the same parts. Always check the most expensive parts in the proposed shopping cart for odd outliers.
This method can get me 95% of the 350 parts I need from two sellers. This requires me to place a small order with a third seller for the final 5%. My solution to this is to keep multiple wish lists (~350 parts each) and shop for all of them at once. Since I just started shopping on BrickLink, I only had one wish list and ordered 97% of it before I realized this solution, prompting me to make a second list. More lists yields more savings, but how many lists should I make before I start placing orders?
Ordering for more than once list at once also requires sorting out the parts you receive into each of the different projects. I haven't done this yet but I assume it could get tedious.