Trend Starter On E-Bay?

I have recently been having a lot of success selling mint Israel sheets on E-bay. Mostly modern (since 1985, when the new currency kicked in). I hadn't seen anyone else listing these sheets recently, and almost all the lots I listed sold. Now, all of a sudden, there are 2 or 3 other sellers listing the same types of material as I have been. I don't think this is a coincidence. Has anyone else noticed that other sellers start to list the same type of item they do?

Yes, I'm familiar with the phenomenon. I've been both the originator and the "copycat". I'm not a frequent seller, but if I can't find a way to lot things for the best chance of success, I don't mind borrowing other people's ideas.

As far as material goes, there is so much out there. It may just be a coincidence that a couple of other people are selling the same kind of material at this time.

adcaplan....did you think you had a monopoly on this??

No, didn't think I had a monopoly, just thought it was curios that for the last year, I haven't seen anyone selling modern Israel sheets on E-bay, and I go and start selling, and all of a sudden 2-3 other sellers list the same items. Personally, I didn't think there was a market for them, glad I am finding out I was wrong :)

I think a lot of sellers are tired of relisting a lot of stuff in their inventory and not getting results that they hoped for . So they watch what is getting bids and what is being sold in the completed section and follow suit and dig through their inventory to list active material.

If I were a stamp dealer, and I relied heavily on ebay for my business, I'd probably study the market trends very closely, and if it made sense for my business (I had available inventory, etc.), I'd probably try to capitalize on trends.

As a collector who sells a few things here and there - pouring the money back into my collection - I do not, for the most part, follow the trends.

ebay tracks how items sell. In the past you could track how items you wanted to sell were selling. Today it can still be accomplished but is more difficult as ebay takes steps to hide identities of other sellers from you.
Search an item, see how many like items are currently on the market. Check "completed listings" to see how much items your interested in are selling for.
ebay also has something called "trends" where the site tracks what items sell for, unfortunately ebay still doesn't understand the collectibles market as well as they think they do, but they are gaining.