Hi windydaboo and welcome to iRv2. Buying an older RV often leads to challenges finding parts, but they usually end up serving well.
Yes, replacement absorption fridges are very expensive. You didn't say what was wrong with yours, so its hard to offer suggestions. It may not need replacement at all, or perhaps a new cooling unit would do the job.
Skylights...did you mean the typical plastic roof vent that cranks open, or a fixed skylight? If the vent, what brand is it? Replacements are usually available, though some brands or sizes can be hard to find.
May I suggest that you ask these questions in posts to the appropriate forum within irv2, e.g. Motorhome Problems & Solutions or Systems & Appliances. You will get more answers that way. It is best to put one question per message.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL