Here a few ideas about where to buy Antique and Collectable Pottery to resell on Ebay.
1) At auctions, these usually have a good range from cleared houses, general public, collectors and dealers. Lots will generally be split into cabinet lots and boxed or tray lots. Cabinet lots can be expensive, I like to look through boxed or tray lots and try to find rarer pieces. Try not to buy lots that other dealers have already tried (and failed) to sell. You can ask auctioneers or porters if the pieces come from private collections or from trade. You can view an auction, do your research, and then bid on the lots you want.
2) Buy directly off the public, try to build up a network of people who are willing to sell to you. They may have old collections of Antques or Pottery and these are usually high quality. Collectors often have rare pieces that will sell well on Ebay.
3) Scouting round markets, carboot sales and garage sales can be a rewarding way of finding Ebay Stock, The early bird catches the worm in these cases. These sources can be cheap but I find this time consuming. It may be worthwhile buying off people who do the scouting for you.
4) Ebay is a great place to buy and then resell. I look for items which have been mis-described. They may have poor photographs or descriptions. I think it is possible to buy a piece of pottery with a poor photograph and resell it for double the original price if it is resold with a clear photograph.
5) Always look for stock you have sold before, this is great because you know the Ebay selling Prices, and you probably have repeat buy customers waiting for you to list it. It is when you build up your knowledge of Antique Pottery from selling, that the process becomes interesting and financially rewarding.