I've done it once or twice but I don't fully get it. Find (or buy, if you're lazy like moi) her a bug and then you get that same bug in return. Is that right? Or am I missing something?
if you buy it you don't get anything except completing the mission. An extra copy of it is not granted.
It's fun? If you don't have the CSS that puts a square around it and relocates it on the page, it's like an easter-egg hunt.
There's an Achievement to collect 30 different ones, although there are fifty of them and it doesn't specify which? Anyhow if you like Achivements, there is one.