>>7458750Walmart (which has cheap sets anyway) often puts them on clearance for less than half their normal price, but you have to get them before someone else does. A lot of Kmart stores went out of business around me in the last couple of years, and I was able to find some nice sets for a really cheap price there.
I get most of my klocki from buying unsorted hauls at garage sales. Lots of people resell it for next to nothing. Last summer I paid $20 for a few opened-but-complete City racing sets, a huge bag of hundreds of Duplo blocks, and several unopened sets. Pic related.