I'll go for a slightly different point of view. Look for signs of maintenance. That roof patch might be a coverup, but it might be a sign that the owners took care of the RV. In the spring many units will still be winterized. Are the lines blown out? Are the tanks empty? Are there signs of caulk applied years apart? So many RVs go many years with no attention and it takes its toll.
Price out tires and a basic brake service for the type of model you are considering. It is not a big deal if a unit has 10 year old date codes on the tires, as long as the price reflects the fact that they will need to be replaced before you can drive the RV.
The fridges in nearly all RVs are expensive to replace. They also take hours to cool down and show proper function. Ask the seller to turn on the fridge before your visit.
Lastly, your budget seems a little "tight" for an class A RV. Prices are often highest in the spring. An you shop at another time? It might maximize your dollar.