I personally wouldn't hire an appraiser unless I was going to keep the items, and then it would be more for insurance value. You can get a better idea of what items are worth by looking at comparable items that have sold on eBay. That is why you want to have a catalog of patterns/potters/size and condition. Not all flow blue is equal-some pieces and sizes are more desirable and collectible than others. If you ever make it to the Spokane/CDA area, let me know!