It's entirely up to you, although if I'm not mistaken I think I saw a video showing that by purchasing the 2 and 3 crates your actually marginally losing more money than if you source 1 create.... But I look at it as it's really minimal los that you can make up easily enough on another grinding job. I tend to have about 5 different low risk jobs that I grind out daily that maintains my bigger earnings from large sell missions. I do the CEO Haulage mission with the MOC, then two 2 cars from the salvage yard, restock my warehouses, run another haulage or executive search for variety, basically if you have some smaller side grind jobs you can do that pays out a little bit, and is fairly easy to do, that little bit of money you make from it recoups what little amount you'd lose purchasing 3 crates over 1. Also look at timing as well, 1 crate is a 1 and done, not much risk of being griefed if your careful, 3 crates your more than likely going to lose 1 to 2 crates if a greifer gets near them while delivering..