I would be looking at Aubiose and/or Megazorb or a mixture of the two perhaps with some handfulls of hay thrown in. Gerbils do tollerate good quality shavings okay, but these days, I prefer to look at safer alternatives that don`t give off the same strong aroma that wood shavings can.
Accessories gerbils love are plenty of toilet roll/kitchen roll tubes, small food boxes (not the coated types though from freezer shops) and ripped up plain white toilet paper as nesting.
Wooden items, but no plastic.
Diet: Burgess do a gerbil granola mix for gerbils that sounds good although it`s not a mix I`ve used as it wasn`t available when I had my gerbils. Silver is currently doing gerbil mixes aswell through Rat rations, but I don`t know if these are still in the testing stage or actually on sale.
Gerbils also love the variety of seeds and grains that hamster enjoy, so flaked grains, jumbo porridge oats, millet seed/spray and the usual seeds and grains that you might find in hamster mixes.