i have been selling on ebay for 20+ years, i agree its not what it used to be & i have reduced my sales there a lot the last few years, but it does have advantages still like world wide exposure & possibility of bidding wars getting you more than you listed the item for, sometimes a LOT more.
the fees are pretty straight forward, they are now 12.9% for auto parts, some categories are a little more some are less, the only "hidden" part of the fee is that they charge the fees on everything, including the sales tax they charge, so when you figure the final amount it seems higher because they charged the fee on the tax & shipping... its still 12.9% but of the full amount not just sale price of the item, its not 15 or 17%. the fee structure is explained pretty clearly. while i dont agree with it, it is not that bad compared to other local auction houses or consignment services.
https://www.ebay.com/help/selling/fe...docId=HELP1456
the $600 1099 thing is stupid too but if you are accounting for cost of goods vs sale prices, youre only paying tax on the actual profits, which technically you should be doing anyways... i called the IRS a few years ago to ask some questions on what qualifies as reportable income, they said even if you mow lawns or do odd jobs youre supposed to report that income. guess i evaded taxes a lot as a kid!
as for how the comp lifters listing is on ebay, i agree with one of the other comments, you have to price things right & just like most stuff, once its used, even if still new, you never get near full price, theres no warranty or guarantee like whats offered buying from the company like summit. with them being $43 more to buy new & free shipping, $600 is not worth taking that risk. auctions usually do much better than a buy it now, but you have to offer some kind of savings on the price over buying new from a large company because as mentioned, people are looking for bargains.