You need to find a niche, something to specialise in selling, you don t need to buy in bulk as this would mean a large investment in stock. I would compare the prices on ebay, look at popular items and see if you can find a shop or website that sells them cheaper. You can start selling like this. Put 6 + items of clothing together for a clothing lot, look out for toy cars, models, pottery, glass and unusual items at car boot sales etc especially those with markings.
what do subscriptions have to do with selling anything on ebay?start with selling your own stuff that you no longer use or need, then use those proceeds to buy other things you KNOW you can sell for more than you paid