Prosper figures his risk at about 14% but when I plug in mor einformation I get more like 4%. I would add 2% for the high credit card utilization to bring it to 6%. Io've asked hima few questions about what he does and his wife's situation. Assuming they pan out I would consider bidding at about 18% or higher (probably a little higher - my estimate involves a fair bit of guesswork).
The way it works is that the lenders read your listing and place a bid with a specified loan amount (at least $50) and a rate that they would be willing to lend at (at or below what your starting rate). Initially they all go in at your starting rate. Once the loan is fully funded (in your case $15,000 is reached) subsequent bids over that amount will bump off the higher rate bids and the rate will start to fall. In general, for both illogical and logical reasons, generating early interest and getting fully funded with time to spare will allow for further bidding to bring the rate down.
There are several ways to do this:
1) Right a good listing that answers all of the questions. If you do not fund and re-list I would incorporate all fot he qeustions you got into the new listing so they are answered.
2) Ask for less. Lower loan amounts fund more easily becuase they require fewer bids and becuase thr isk of default is less so peopel are more willing to bid.
3) Start at a higher rate. Sometimes you end lower by starting higher. Just be careful, if you find and then turn the loan down to try again for a lower rate it is off-putting.
4) Join a group. The leader will likely ask you for more information, including personal contact information and possibly financial documents, but if he endorses you then his group members will bid early and if not fully fund you generate that early "buzzz" that can make all of the difference. Before joining I would look at previous group listings to see if the group tends to bid on its own loans. You can tell because in a group sponsored loan group members bids have a little three person symbol next to their screen names.
5) Get friends or family to bid some money. People take it as a good sign if people who know you personally are willing to bid. Your mother and wife probably don;t count (I've seen people do both of those - I think it just striokes peopel as odd. Keep in mind that it will take them at least 4 days to get registered and money transfered into their accounts so if you are going to do this give them a head start before listing.
In your case you fall victim to some of the holes in Prosper's risk estimation tool. They don't look at all the factors on the screen. They estimate your default risk as 14%. That is why they suggest, and many borrowers expect, you to start at about 15%. If it bids down a few points and ends up in the mid 20's% then the return after defaults is in the 8-10% range. Using more data (still prosper data) I calculate your default rate at more like 4% plus another 2 for the high credit card utilization - or about 6%. The average prosper loan defaults 14% of the time so this is not bad at all.
There is a lot of dumb luck involved as well. Sometimes people relist the identical loan request several times before finally funding. For instance I do not currently have funds in to bid but if I did might bid at about 18-20%. I put it on my watch list and if something frees up still might.
http://www.prosper.com/lend/performance.aspx?af=0&esba=63&gm=0&gr=0%2c1%2c2%2c3%2c4%2c5&hw=0&iba=255&ibid=0&iwatch=0&lc=0%2c1%2c2%2c3%2c4%2c5%2c6%2c7&lq=&maxAmt=18000&maxDTI=0.4&maxFund=1&maxGrpTLC=1000000&maxND=0&maxPR10=0&maxQ6=1&minA=0&minAA=0&minAmt=13000&minB=0&minC=0&minD=0&minDTI=0&minE=0&minFund=0&minGrpTLC=0&minHR=0&minNC=0&minND=0&minPR10=0&minQ6=0&occ=&od=10%2f11%2f2008&oer=01%2f01%2f2008&osr=11%2f01%2f2005&plcgd=&plp=0&sf=10&sh=0&sn=&tg=0
