i tried a DIY solution while waiting for a cheap enough one on Ebay, i used 3/4" chipboard which wasnt too bad but did tend to bow slightly, keeping turning it over worked ok for a temporary fix,
i found a cheap enough part on ebay, was an open bid which i managed to bag for only £15 + £5 p+p
bargain as Nissan wanted £80 inc vat for the one i needed (biggest one)
keep checking e-bay and bide your time, im sure you will get one eventually.