I am not familar with a class called a Sun Chaser but do have a suggestion or two. First off if you are interested in performance
dinghies I would visit places were boats are raced in your area. In most locales there are one or more popular one-design class that is raced locally. The models that are popular tend to vary with each region (or even with each sailing community with the region). Within that area examples of that model can often be found in reasonably good condition and for reasonably inexpensive prices. These popular classes often include older models that are available at very inexpensive prices (around here, the Jet class is one such example). The other nice thing about these popular older classes is that if you take care of them you can often sell them fairly quickly and for a price that is something like what you have in them.
One-design classes are often anxious to encourage new members and so will often invite you to try out a model that you are interested in or may have a class ass''n owned boat that is available to borrow.
Jeff