An eBay reputation is important if you're going to sell there. Research shows it adds a decent amount to the price, and it's very difficult to sell at all with just a few feedbacks. Usually sellers will buy a few items first to get a decent feedback -- sometimes even scam items sold just for feedback. Because savvy buyers insist on selling feedback, it's harder, and sometimes sellers will also sell bogus items just for feedback as a seller. eBay has considered offering a feedback score based on the dollar volume of positive and negative transactions but has not yet done this. Some plugins will do that.

One thing I recommend to low feedback sellers it to offer to reverse the "normal" payment system. If the seller has little feedback and the buyer has much better feedback, the seller should send the item without payment, and the buyer pay on receipt. Many people find this foreign but in fact it makes perfect sense. In real stores you don't pay until you get the item, and many big reputation merchants allow payment on credit for known buyers. Another idea is to offer to pay for escrow. This costs money, but will make it back in higher sale prices.

However, here's a new idea. Allow high-reputation sellers to "lease out" feedback, effectively acting as a co-signer. This means they vouch for the brand new seller. If the new seller gets a negative feedback on the transaction, it goes on both the new seller's feedback and the guarantor's. Positive feedback goes on the seller and possibly into a special bucket on the guarantor's. The guarantor would also get to be involved in any disputes.

Seems risky, and because of that, guarantors would only do this for people they trusted well, or who paid them a juicy bond, which is the whole point of the idea. Guarantors would probably use bonds to issue refunds to badly treated customers to avoid a negative, though you want to be careful about blackmail risks. It's possible the breakdown of true and as-guarantor negatives might be visible on a guarantor if you look deep, but the idea is the guarantor should be strongly motivated to keep the new seller in line.

With lendable reputation, new sellers could start pleasing customers and competing from day one.