Additionally, it's clear within 30 femtoseconds that the site is geared towards musicians. Nice work.
Now, for the money. Quickly, QUICKLY implement automatic (affiliate-based) listings for the music gear on eBay. People will click on the links and if they do AND they buy, you get a commission. It also provides you with a HUGE inventory of equipment out of the gate.
Also, give people a way to load their listing by simply giving you an ebay auction ID.. (ebay has an API for this), and it will become the thing to do.. post an ebay auction, then list it on PeerGear.
Finally, once your natural inventory grows, you can limit the number of ebay auction listings per category to focus on your own user base and keep traffic local.
Cheers! Randy
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