Don’t buy anything that wasn’t inspected, by an inspector you paid. Use the inspection report to inform your negotiations.
A 2004 coach greatly exceeds the 10-year rule that some parks have. You can get exceptions to this rule when your RV is in good shape, but be aware that there may be times when you have to send photos of your coach ahead to a park you want to stay at
Ask for service records. Review them. That will give you insight into whether the unit has some persistent issues.
Parts for a 14 year old RV are likely going to be a bit harder to find. When you do find them though, they’re likely to be pretty cheap.