The Gutenberg version is abridged, and the translation is also much worse than Trask. I do not consider $20 too much for a 800 page 2-volume book, very well typeset, with plenty of notes, and huge scholarly work put in it to make it accessible to the modern reader.
Still, it seems a wee bit ludicrous to be paying money for a work created over 300 years ago. Even the translations are still only derived works.
[0] https://www.gutenberg.org/ebooks/2981