The market is telling you a great deal of information. Research what other Reattas of the same year, condition, mileage have sold for and let that be your guide. Be realistic. I have learned a valuable lesson over the years, what something is worth to you is of little consequence, rather it is all about what someone else will pay.
I had the task of selling a 1985 Corvette, black on black with the Doug Nash 4+3 manual. Fair condition, needed some cosmetics fixed, but overall a solid foundation. I played around with price, went down, de-listed, relisted up in price. Ended up selling it to someone who had a perfectly similar vehicle, colors and options when purchased new. Then came marriage and children and his Corvette was the first thing to go as it was impractical. Once the kids were out of the house, a search for the fountain of youth led him to purchasing the car for full asking price, no questions asked. No haggling.
The challenge with the Reatta is they were not targeted at a younger generation, rather it was older folks. Unfortunately there is less of a look-back for people who were in their 50's when purchased new, and are now in their late 80's and 90's looking to buy one again.
For me, I hang onto ours because it belonged to my father. I smile just like he did when driving it, and his spirit rides along with us wherever we go in it. The value to me is far above what anyone else would pay.