It's good that you're looking with a critical eye, and not just with your heart. I know with a fast-paced market it can be difficult to take your time to ask the right questions and thoroughly look over a rig, but with enough time you will find the right rig for you. The most challenging part is balancing the purchase price versus purchase+repair price. Is a more expensive rig that doesn't need as many repairs the right answer, or is a cheaper rig that you need to spend unknown dollars to repair the right answer? Tough call.
Good luck on your hunt.
SMB-less as of 02/04/2012. Our savings account is richer, but our adventures are poorer.