Sell everything or not?

Replacing everything is going to cost you more than $1500. A good queen size bed alone is going to cost you that much. Plus add in other furniture (couch, love seat or chair, dining table and chairs, dresser, etc.), electronics (TV, computer, stereo, etc.), small appliances (microwave, toaster, etc.), and cooking/eating supplies (pots and pans, dishes and bowls, cups and glasses, cooking and eating utensils, etc.), and the costs will be quite high.

Unless you have the money and really want to start all over, I would move what you really need, and sell off everything else.

We cannot help as we don't know your lifestyle so have no idea what items you cannot live without nor how much you can afford to pay for them.

Personally I could not furnish a studio apart. with $1500

you obviously cannot take everything if you are downsizing that much - doesn't seem worth the cost or hassle - especially if you can get a few $100 at least for stuff you can't take - sell it all and just take what fits in the car

To buy everything all over again, brand new is going to cost you a bundle. Things of little value, leave them behind. Take with you anything of value that is irreplaceable and the items that are going to be costly to replace. $1200 to move is nothing. Take what is costly to replace, important, sentimental and, antiques.

Rent a furnished studio apartment and sell all your furniture.