Regardless whether you are modifying official LEGO sets or building MOCs you will likely need to have additional parts. Here are some suggestions on the best places to get LEGO parts.
This is the most convenient way to buy parts if specific sets have a lot of the parts you need. Most sets will have a wide assortment of parts that you can use for modifications and you will get extra MiniFigs as a bonus.
LEGO also sells “Creative Brick Boxes” that include an assortment of bricks and parts that can be very useful. Some of these boxes are exclusively sold through certain retailers like Toys R’ Us (depending on the country you live in).
Here’s a tip. There are often sets and boxes on sale with heavy discounts at certified LEGO stores. You can save quite a bit of money by buying these discounted sets just for the parts, even if the set design does not interest you.
If you happen to live in a city with certified LEGO stores, you can buy parts from the “Pick-a-Brick” wall. You basically fill up a plastic container (two sizes available) with as many parts as you can and pay a fixed price.
You can often get a good deal based on a price-to-parts ratio but the selection is very limited and it is unlikely you can get all the parts/ colours you want at any one time. However, it is a good place to start and stock up on parts.
You can also buy parts from LEGO.com but the selection may be limited and shipping can take several weeks, depending on your location.
If you require specific parts, Bricklink.com is currently the best option available online. Bricklink.com is a marketplace for buying and selling LEGO. You can buy sets (current or retired), MiniFigs, and individual bricks of all types and colors.
The way it works is very similar to any other online marketplace like Amazon. Sellers post their items for sale which you can purchase after creating an account. Like any online marketplace, compare prices and shipping costs to determine which seller will give you the best value for the parts you want to purchase.
The benefit of Bricklink is that you will be able to get almost any part you need. The price you pay depends on the supply available and the location of the seller in relation to you.
It will take you some time to familiarize yourself with the system and the names of different LEGO parts as it is quite a large database. If you are confused in the beginning, do not worry. It can be very overwhelming at first so take your time browse the site, read the FAQs or pop into the chatroom.
While not a first recommendation to get parts, if you are not looking for specific parts and are just looking to stock up on a variety of parts in different colours, you can find good deals or hauls from eBay.
In most cases, the bricks will not be brand new. So, if this is not an issue with you, you might be able to buy 1000s of bricks at a good value.
If you have any other sources for LEGO parts, let me know and leave a comment.