I just submitted a simple but fairly large [21" x 16" x 2"] slidy-lid box that I designed in easyeda for a quotation. The cheapest I could get ["9600 Resin", even though I don't want white; none of the other technologies would print the box [too big]] was $64 for ONE lid [a flat piece of plastic with no features] and $64 for ONE box.  "JLC Black Resin" was $138 for one lid plus $135 for one box.

And shipping for ONE PIECE was another $100 [which I could get down to just $70 by switching to UPS].

What in the world am I doing wrong? $370 total for a plastic box that could hardly be any simpler?  Is JLC3DP just n ot practical for larger pieces like this?