TLDR; We tend to overvalue things we build ourselves.
This experiment shows that when we use our own hands to build something, we tend to value it even more than higher quality items. I've personally experienced this effect many times in my field (software development). We call it "not built here syndrome". While there are perfectly great off the shelf alternatives, we tend to feel that by not building it ourselves it just won't be quite as good. Very often we underestimate the skill and time involved in building a product of equivalent quality.
Watch the video for a great overview of this bias.