What was your "repair specialist" indicating when he said the glass can be replaced? All single pane glass can be replaced, however, as Millworkman said, most older wood windows are not well suited to accommodate a dual pane IGU. The added thickness and required material removal from the wood sash often weaken the window to a point that is not acceptable to anyone else but the person selling the service. Fiberglass is a fine option but will come at a premium but may give you the look you are looking for. Good vinyl does not yellow so put that out of your mind for consideration.

Based on the extent and difficulties associated with repairing a non-historical window, you would be better suited to get altogether new windows. The only thing left to consider would be whether or not the replacements would be inserts of full frames.

The answer to your question depends on where you are financially and what the house is like. I'm thinking this is not a colonial mansion in Moorestown, NJ. The vinyl siding gave it away. With that in mind, there is no way I would spend that much money on those particular windows. I would replace the rotted parts of the sills. This is most likely only the outer 2 inches or so, where moisture has been trapped under the ext trim. I would also replace the brickmolding (ext trim). I would then have these openings wrapped with the aluminum of your color choice, making sure that that is sealed properly, and also installed behind whatever drip cap is above. What I'm describing is not expensive work, perhaps app $200 per opening, including material. It is also not time consuming work, and fairly straight forward. I would then choose a quality replacement window with an insert installation, preserving all your interior trim. I would think you could have all this done for less than $1k per window or so. It could be argued that the technically correct way to do this right is to gut the openings and go with full frame methods, all new everything in and out. But replacement windows are called replacement windows for a reason. It is not always desirable to replace everything. For instance, if those wood windows of yours have a rope and weight balance system, then there is a large weight pocket behind the jambs. It's just not worth it to take all that apart unless you're wealthy or doing it yourself. Just get the best window you can. I suggest fiberglass framed so that you won't lose glass space. If that doesn't bother you, high end vinyl will work as well. But don't skimp on the window. If you do, you will be back in the same boat in less than 10 years. One more thing. The aluminum wrap on the outside can be bent in such a way to have a brickmold profile. This is much more professional and attractive, and shouldn't cost any extra if you have true professionals doing the work. Good luck!

Mary, Are you referring to window restoration or just sealing up some existing windows? The two are going to be very different type professionals. If it it just sealing up some exterior trim on windows, a decent painter can do that. If its window restoration, that is a different ball of wax. Window restoration is a very niché marketplace. The best thing to do is start with a Google area search near your home and especially in those areas that are more heavily concentrated in older homes. Next would be to ask around any of the historic districts that are in your area and see who they might have a list for. Hope this helps.