If it's a modern high frequency switching design, it won't need a lot of copper unlike the ancient design that Trace, Magnum, Xantrex, Tripp Lite and others use. Those low frequency designs need huge inductors to carry massive current between switching intervals. High frequency = less current to carry between switch cycles.
To me the chart at the bottom, listing a 1500 watt inverter for a 20 watt fluorescent, is just over compensating for surge current. Big caps to handle surges make things expensive and were left out to meet that $300 price tag (which is probably 2x mark up)
