My opinion is the prices for those weeks are way overpriced as the two weeks you are looking at have lower, trading value because they are in less demand times. Be patient, make sure you are comfortable with the price and do not assume what you pay you will get back. Assume you will have to give it away when you no longer want it. Even if today it has value, next year it might not.
If you look at sharket.com you can see price ranges. Lots of units have sold. You can’t tell which weeks but my assumption is off weeks are in the lower range.
I can only compare this to Marco Island in pricepoints which is about a 1/2 hour away. I got a week 50 at hgvc surf club, 2 br , from a fellow tugger for free. I got a week 51 at sunrise Bay, 1 br, from a fellow tugger for free. I purchased an off week, week range you are looking for, at Sunrise Bay for $1000 including closing costs from the association and with this one I felt I overpaid but was ok with that. I accept when I no longer want it I will be giving it away. At lower price ranges these units are being offered, I got winter flex weeks at eagles nest at Marco Island 2 br and surf club at Marco Island 2br.
Have you visited the timeshare in the area? If not, on your next visit, visit them all. Speak to the managers , they know about HOA sales and people selling. If you go visit a week you want to buy and walk the pool area and talk to owners you might find out one of them wants to sell. This happened to me for a week 50 at a sanibel resort. Just talking three owners told me they would sell if I was interested. I got the free hgvc surf club instead.