CuriousInventor points out this head-slappingly simple substitute for standoffs – likely of interest to anyone whose marvelled at how much these bits of hardware can actually cost –

Tan Tran came up with a cheap substitute for aluminum standoffs: nylon tubing. Polyethylene does a decent job too, and can be had for under $.10 a foot at your local hardware store. The 1/4″ OD (outside diameter) stuff shown in these pics accommodates up to #8 size screws.