Quote:
...Other sites that try to cater to collectibles use the same model...
Agreed, they use a business model which dictates they cater to their shareholders, stock price, and profitability.
The issue here is building, implementing, and supporting a worldwide online auction infrastructure that makes very small stamp transactions worthwhile. Saying that you want to support hundreds of thousands <$5 dollar online transactions is not exactly a business model that will attract investors, a small business loan, or even allow you access to high interest business loans.
Consider
Amazon, it took them 20 years before they turned a profit…

The name of this game is 'cost per transaction'.
Don