Goldstream camper- deal too good to be true?

Being new to this forum, I would like to ask a question as this site seems to be a wealth of valuable knowledge. We are in the process of buying a wind up camper a la Jayco, Goldstream or Coromal and was wondering if the following purchase sounds ok or if we are being sold a lemon. We have been offered to buy a 2007 Goldstream Star 2 camper, on road version with no bells and whistles (no annexe, deep cycle battery, etc). The owners are asking $12k for it. We had a look at it yesterday and the interior appears in excellent condition. The exterior however is a little bit worse off. I know that this van has sat in the weather for at least 2 years, so plastic covers to power points and water tank has degraded. The canvas had surprisingly not rotted and just one repair patch on one of the flys to the queen bed. The bag awnings may be worse off as there was some mould on the exterior zippers. The undercarriage looked neat and clean, no breakages just a little bit of surface rust on the leaf springs. Wind up works fine, door fitting good, the camper comes with 12 months rego. What do people think, does this sound excessively cheap for one of these campers (I have no idea of what they normally cost) and should I be worried??? Should we go for a different brand instead? Grateful for advice!