Plastic Headlight Covers
 

I have an older car with very low mileage and although it's garaged I work and it sits out in the sun all day...the headlights have yellowed and I have tried everything from nail polish remover...to headlight kits to having them sanded which worked for about a year for a cost of $125.00. I was wondering if anyone has ever had them replaced and a recommendation

Have you searched the Internet for auto parts stores and also Amazon?

I found some on Amazon but I need someone to change them or I need to know if it is possible

I had a 97 Buick I changed the headlight unit. Wasn't a big deal on that car.
Bought the lights on line.

I bought my granddaughter, an older Honda several years ago that had that problem I used automotive rubbing compound with a buffer and they came out looking like new. You could probably do it by hand the buffer just made it easier.

I think the Sam's Club automotive section sells a product to clean the plastic covers, and they may even do it for you. But, I would opt for new covers if I could.

Have you tried using toothpaste (with a little baking soda if you have it)?

Rub covers with it on a damp cloth, rinse off, polish with a dry cloth

If you then smear a bit of olive oil on them the finish should last longer, but this is optional.

I have restored the 20-year old covers on my headlights three times doing the above.

there is a buffing cream compound that is available that I've used, but I thought the toothpaste worked equally good. they won't come out like new, but quite a bit better.

Replace them, there are no other options that will work for very long. As you probably already know, these days, headlight assemblies are usually very expensive.

This would be my suggestion.

Check on you tube for replacement for different models.
Some vehicles are easier than others to replace the lenses.

If you can supply some details, make, model, etc., I may be able to help. I have rebuilt 8 cars from the ground up, but a lot depends on how the lights are mounted, how the lens are attached, etc.
Feel free to send me a PM if interested.

Another vote for toothpaste. It is a mild abrasive (use paste, not gel) and it will take off the surface oxidation that causes the yellowing.

Sanding is too extreme - and expensive!

Back in Jr high shop class made some plastic ornaments. To polish them to crystal clear used a buffer and jewelers rouge. Most toothpaste has some kind of grit in it.

Agree with toothpaste solution, it has worked for me.

Polishing kit
 

I used a "headlight lens polishing kit" that I bought at Harbor Freight. Fairly inexpensive and worked well. It's designed to work with a hand-held 3/8" drill. Took some time, but it wasn't physically demanding. Starts with a more abrasive pad and finishes with a finer one. Includes the polishing paste. Sorry, I don't know much about replacing a lens.