This past weekend, I made a stop to TRU to find a Vader talking toy for Madman.
Sure blame me! Just kidding Pete

. I've also found myself sucked into the darkside sort of. Like I've said a few times. I'm not a Star Wars fan. When TPM and AOTC movies/toys were released, I really had no desire to pick any up.
However, after watching ROTS the other day, I picked up a few figs and was tempted to pick up some more (like clone troopers and some droids)but reasoned myself out of this. In my opinion, most of the figs aren't that great. I hated action attack on joes and I still hate them on SW figs. I picked up a Vader and Greivous. I don't think I'll be purchasing anymore of these though.
As Spill said, it's because Star Wars toys are everywhere. You walk into walmart, zellers, TRU, local comic/hobby shops and there they are.
If you think it was the spur ofthe moment purchase, like you said, you can return/get rid of them later.