Isn't market X already serviced by company Y?

I like this question, especially when it comes to defining niche markets. The answer is almost always "yes" - there isn't a market uncovered:

1. When eBay started back in the mid 1990's, their market was covered by garage sales and flea markets.
2. When Google started, their market was covered by many competitors.
3. The online advertising market existed before Google - why did they choose that business model?
   
4. When MySpace entered the picture, their market was already covered by Friendster.
5. When Amazon opened it's virtual doors, their market was already covered by retailers
6. StubHub is in the market of P2P ticket sales - eBay has that category and covers that market.

And my favorite example is Etsy. Their market (Arts and Crafts) is definitely covered (and extensively) by eBay. Even with Arts and Crafts being extensively covered, eBay still has a hard time doing it well. A service that focuses on one niche is always better than a service that does it all. The one good thing that eBay does well is that it does a little bit of everything - On the flip side, niche companies do a whole lot of one thing and can be pretty damn successful at it.

The only time I would be afraid is if a market isn't serviced by anyone. There's a reason it's not being served.

How does this apply to Wantsy?

Craigslist (and a few others) already service the wanted ads market. But what good is it to the users when the majority of the traffic isn't going to those wanted ads? Wanted ads, like all other listings, need to be sub-divided into categories themselves; something not done on ANY other site at this time. Instead, wanted ads are their own category with nothing below. There is so much potential with wanted ads, and I definitely don't want to see it wasted.