I just started to investigate the possibility of buying some notes and located a few  websites that seem to be popular. I have also signed up with Dave Horns .I also meet a vendor at the note show who has a website called

https://notelinq.com/

http://www.pprnoteco.com/notes-for-sale/

http://www.fciexchange.com/

http://www.loanmls.com/

Any others that anyone could recommend ?