Rare antiques can bring in hundreds—even thousands—of dollars. However, not everything that is old will get you a fortune, though, which is one reason why it's important to be able to identify an antique when you see one.
In most cases, a professional appraisal is your step one to knowing what might be valuable—especially if you have a roomful of antiques. You should still research the item to find its potential value on your own. Some antiques require a trained eye, while other antiques may only need an Internet search on sites like eBay or Barnebys to find out what people are willing to pay for the item.
If you decide to sell an antique or collectible online, first you must establish yourself as a reliable dealer on that popular site so that people have confidence in the items you have for sale as well as confidence in your shipping practices. Don't forget that, on these sites there is a big group of available buyers, and there may be stiff competition, too.
If you think it will be better to go through a dealer, remember that the dealer will need to make a profit. Have in mind that the value depends on the current economic situation, the region where you are attempting to buy or sell the piece, and whether or not someone will actually want to purchase the item and whether a similar item is available in the shop right down the street.
Take good care of your old things. Keep them out of harm’s way and do not attempt to refinish a piece of old or antique furniture. Part of the value of an old piece is determined by its patina, the changes that occur in the aging process. If you remove old paint or finish, you may destroy both the charm and value of the piece.
If you have old textiles, prints, paintings, or photographs keep them out of the heat, moisture, and light. Also consider using gloves when handling them because body oil can transfer and damage these fragile pieces. Never attempt to frame or remove an old photograph, print, painting, or textile from its frame. This is best done by a professional or an expert who knows how to handle such a fragile piece.
If you have a specific piece that you're looking to find some pricing information on, you can check with other websites that provide realized sales listings or professional appraisals.
Search at Antiques Roadshow. After all their appraisals over the years, you can find prices for just about anything (https://www.pbs.org/wgbh/roadshow/season/3/hartford-ct/appraisals/homer-laughlin-fiesta-dinnerware--199807A34/)
If you just do a bit of searching, eBay has a handy way to look up realized prices for any antique: you can do a search and under the "Categories" column to the left of your screen, head to the bottom and click on "Sold Listings."
Voila - realized sales for comparison.