This is in addition to the time spent buying food, cleaning cages, preparing food, etc. An iguana owner should be willing to make the effort to find a good vet for the iguana, even if it means driving for an hour to get there. If the prospective adopter doesn't feel a vet is necessary, then you may want to reconsider this person. Iguanas are expensive. If the prospective adopter seems to be reluctant to pay for the basic need of the iguana, then they may not be a good person to adopt to.
Experience helps, of course.
However, do not turn down a prospective adopter because they do not have prior experience. Someone who has researched iguanas, spent time with them, understands the needs and the care involved, can make a very good owner even if they have never had one before. It just depends on the feeling you get from the adopter. You want your prospective adopter to be well prepared to bring an iguana into their home. They should be able to tell you what an iguana eats, what temperatures it needs, what foods it should avoid, if it needs UVB exposure or not, and other aspects of iguana care.