First time buying Lego with investing purposes

Hey all, I was looking at buying something for myself for Christmas and saw the Himeji castle set, so i decided to get one. When I was about to finish the purchase i saw some more sets that were discontinued from the official Lego store. I'm based in Bulgaria, so I guess a lot of the stores here have leftover inventory. I remembered that some time I ago someone had mentioned to me that Legos have good resale value, so i decided to get some more sets with the intention of reselling them down...