I cover my TT with a piece of silk from a 2nd-hand-store Hawaiian Shirt (about $5).
I cut-out the back panel, then my wife quickly hemmed the edges. It is cheap, works as well as the plexiglass cover that my other TT has and is very light.
Warning - learn to remove it from the rear, moving to the front, to avoid snagging the cart.
Cheap, works well and looks cool... This has worked for years. Wife optional.