I've never understood what those numbers refer to, they're mentioned in the table but nowhere else that I've found. They're NOT numbers for free listings. I've never had a free listing all the time I've been there. I'm a Silver level seller and use Platinum Listings @ 5p a listing or re-list, they are like a pay-as-you-go version of Platinum level seller.
Platinum level, with the up-front fee, is the only level with free listings/re-lists and reduced FVF, that's what you're paying for. It depends on how many items you have to list, how long they take to sell and (crucially) how crowded your category is, whether it's worth paying or not.
If you have 10K stamps to list in a category with a million others to compete with, it's worth paying for. I'm in a niche vintage glass category with less than 300 items in total (mostly my own items), so I've never seen the need. You will have to look at your competition and decide. The big advantage of Platinum listings for me is it gets me access to the Paypal integrated checkout (which you also get with the Platinum level package).
Whichever level you choose won't magically increase your sales. The site is still tiny compared to ebay, there is far less footfall and passing trade, it's up to you to get your own buyers without relying on the site's marketing dept. -- they don't have one.
Over the years I've built my 'inventory', reputation and some repeat buyers which has helped me do better there for the past few years than I have on ebay. Last year I sold 28 items there and 5 on ebay (and those five cost me double the fees and infinitely more time and hassle as I listed the same number of items on both sites).
A variety of items do sell there (look at the Recently Sold strip on the HP). It's small enough for you to become noticeable in a smaller pool of items and they do up-load your items to GS (with conditions so see the Help FAQs)
It suits me as I'm just selling off a lifetimes collection of glass and it does sell, slowly, surely and cheaply. It wouldn't suit me if I was trying to set up a business needing a quick turnover in multiples of a few items. One thing I've often said here is that I sell stuff there because buyers can find my items easily, not like on ebay where they're virtually buried under Sponsored listings on a site that is designed to squeeze fees from sellers rather than sell their goods.
