Hi Ted, thank you for reading and also for your question. It is a very valid question and answered in multiple ways depending on if we are talking about individual parts or complete sets.

What I am selling here through these marketplaces is specifically individual LEGO bricks. It is true that to a degree Lego offer a very similar service, called Pick A Brick and do have quite an extensive range available. However, this comes with a number of flaws. First it takes 15-40 days or more to deliver depending on the parts ordered. Depending on the part this can be quite expensive and has fees and delivery cost for small orders.

This is where sellers like myself come in. I can provide items quicker, generally delivering within a week. I also am able to offer parts that Lego may not manufacture any more depending on how and where I have sourced the items. While some of the items might be used, they can help a builder finish a set or design they are building.

Which brings me to another point is that when building their creations, it is not always cost effective for a builder to go and buy the parts they need in sets. For example they might need 100 of a specific part to complete their design. To get that part in a set, may mean they need to purchase 20 copies of a set which contains five of that part. This can become cost prohibitive for some. But for my business I might have purchase this item in bulk to resell or purchased multiple copies of specific sets to have the parts available to resell.

In regards to sets, Lego make a set and make it available for sale, anywhere from 12 months to multiple years. But eventually they retire the set from sale. There are very few sets that spend more then 2 or 3 years on the shelf. This gives people like me the opportunity to buy some of the sets prior to them being retired from sale. Once retired the market starts setting the price. The less new sets available, and the greater the demand for them the higher the price.

Again thank you for reading and I hope that this helps to answer your question. I will be sharing some more stories in the near future covering some of these bits of information in more detail.

All the best
Joel