Photo from Pinterest -- I've tried to enlarge this, with no luck. You get the general idea.
Here's a source of easy, inexpensive (well, sort of) greenhouses and seed-starters.
Many take just a little scrounging to find the proper materials...like the rotisserie chicken container used in the first photo below.
Earth Easy has a particularly interesting one: making rounded 'cloches' (hoophouses) using cedar twigs and plastic. Easy and effective.
|Earth Easy photo|
Maybe I could at least start some greens?