I don't know if "regret" is the word I would use with a lot of my non-Transformers toys, most of which I gave away for free last year. Because I did get a lot of enjoyment out of them until I became a parent and had to streamline my hobby solely to Transformers. But they were well loved toys until my daughter was born. But after that they just sat in boxes for 5 years, which was just ridiculous... not a believer of keeping things in storage that don't see the light of day, so I gave most of it away. I wish that I'd been more proactive in selling them maybe (but even then, it's hard to offload everything), but I don't regret actually collecting them.

DVDs/BRs on the other hand... often I buy something because I liked watching it once or it looks like something I'd enjoy, and yeah, I'll enjoy watching it first couple of times, but then lose interest. I'm a lot more selective now in terms of what I'll buy on DVD or BR. I'm a frequent renter at my local Blockbuster, or sometimes I just wait until it's airing on TV. Definitely not a fan of collecting TV series. Another one is comic books (non-TFs). Yeah... a lot of stuff that I need to either sell or give away.