I called my lfs, they have one for $10 since it's used, said $15 for a new one.
For that price I'll drill a small hole in a piece of plexiglass and set it on top of the filter to cut down on evaporation. It's not a show tank, just a 75 gallon in the basement for growing out fry. The glass tops are two former stereo stand doors. Tempered glass, they hang out over the back a couple inches but serve the porpose well enough.