It's all about driving qualified traffic and none of the sales venues such as eBay, Mercari, Amazon etc. allow sellers to drive buyer traffic offsite, its a policy violation worthy of suspension.
Using social media to drive traffic towards you're eBay items is fine but you can do that w/o Shopify. As storefront packages go Shopify is very expensive at $400+ a year when one can buy their own hosting and install a shopping cart for far far far less money. But again the issue is driving traffic, its not automatic and there are many mechanisms to do that but most require an education to some extent on technical matters as well as a good underpinning in marketing. 98% of all "I'll make an online store!" webstores fail to deliver because the folks doing so fail to get the education and fail to do the work. Then they hire someone do it for them and get all bent out of shape at the costing of that.
With tools which you seem be selling as is the case in brick and mortar or online, quality tools sell, sell for more than those that are fair at best and/or poor quality. There's quite a bit of competition in tools, myself, I don't even bother to buy any tools online... I find good quality tools at yard sales for fractions of what they'd cost me buying in retail or from online third party sellers.
