(Undated)  --  Shoppers in the Portland area are expected to spend below the national average on holiday gifts this year.  A new WalletHub study ranks Hillsboro 165th among 570 cities surveyed, with an expected average of 788 dollars, compared to the national average of 935 dollars.  Portland is 256th in holiday-gift spending with an average of 643 dollars, while Beaverton is 317th with 581 dollars.  WalletHub conducted the study using figures from the National Retail Federation.