The only time I've ever made money on ebay is when I latched on to a fad of the moment. My best selling experience was when I made checkbook covers with photos of Clay Aiken when all that American Idol craziness was going on. I was selling them faster than I could make them! AI is now so mainstream that they wouldn't have the same result if I tried it again.
It's like pillow pets. They were on tv constantly, drilling into the minds of children that they needed on and they were sold out. The smart folks stocked up and then sold them on ebay when they were sold out online. They were selling for more than double the original price, sometimes as much as 4 times! Now you hear absolutely nothing about pillow pets.
Seems to me that cashing in on fads is the way to go, and for things related to kids because sometimes parents are willing to pay more to make their kids happy, especially around Christmas time.
As for hard to find items, this may be a dumb question, but if it's hard for others to find, isn't it going to be hard for you to find?
I've talked with several friends about ebay and they all say they don't even go there anymore because they can find better deals on Craigslist and they don't have to pay ebay or paypal fees.
Can I ask what your ebay store is? I'm curious to know what you sell :)
I know I wasn't any help, but I'm inclined to say that rare toys or old school toys that invoke memories in adults might be something to look at.
Is there a way to do some sort of search to find out exactly what people are searching for on ebay? That might also help.
Best of luck though. It's a tough world right now and I think many of us are looking for a cushion to help us get by.