What do you do if you find your stolen bike's frame on ebay? I am 85% certain that I see my bike's frame on eBay. It costs almost 2k with all the components and I see the frame on sale for $400 with seat-post and fork only. All my stickers not in the pictures(3) however the frame is the same size and picture only shows the side with no identifiable mark. 

The frame itself is rare, not expensive but the brand is not widely sold. And if its sold used, its almost always a complete bike. The manufacturer doesn't sell frame only.  

It was stolen, from a bike rack, in open daylight in downtown in big city, I suspect that I forgot to lock it. Lock was on the frame and so was my helmet. I reported the bike stolen on bike index and did file a police report. And posted the bike on local FB groups for stolen bikes. 

It is now on sale on ebay, 5 days after about 100 miles away from where I am. Item says local pickup only? 

UPDATE: I am now less certain that it is indeed my bike. More like 40%
To determine if the bike is indeed yours, you could contact the seller and ask for more information about the bike and for more pictures in the hope that you'll get one with a visible identifying mark.

You'll need to be careful. If the seller know's it's stolen asking for more information and pictures could tip them off that you are the rightful owner with the intention of retrieving your property.

You should read the Ebay Stolen Property Policy for what to do if you are convinced the bike is in fact yours.