Hi, I'm mainly a drummer but have played bass guitar for over 20 years, some of that time professionally. However, I'm totally new to double basses and have only played them a few times. What are some good basses for a beginner who will mostly be playing jazz and an amateur level? Are those really cheap ones on eBay worth considering? I would be interested in one that's as affordable as possible and is fairly durable. Also, any recommended books for DB beginners interested in playing jazz? (I don't know the positions or anything and can just barely read music for bass guitar.) Thanks a lot.