Hopefully you saw that in time. Now for a more thorough answer.
Value of coins isn't dependent upon age, it is based on a combination of condition and rarity. Small differences in condition of coins can make a major difference in the value of a coin. For example, an 1892-s Morgan Silver Dollar in AU (almost uncirculated) condition is worth about $5,000. The next higher grade - MS60 (Mint State 60, 70 is the highest possible rating) would be worth about $34,000.
Of course, if you took your can of silver polish to the coin, that $5,000 coin might be worth $2,000.
A less desirable coin would suffer an even greater loss in value, and common coins could become unsellable.
The first thing you want to do is get a rough idea of the value of the coins. A good resource is PCGS's website. If you go to www.pcgs.com/prices , you can see the retail prices of any American coin. Don't worry about how they grade out yet. Just find out if you have rare coins, or common coins. (If you have anything interesting, you can either post a picture here, or whisper to me for my email address and I will be glad to help you out)
Should you have anything valuable, you should submit it to be graded. Though there are a lot of companies that will grade coins for you, you should only trust PCGS, NGC, or ANACS. You can only submit to PCGS or NGC through a coin dealer (I have used Huntington Beach Coin Exchange to submit raw Carson City Morgan silver dollars, and can recommend them as being honest. Their website is
http://www.huntingtonbeachcoinexchange.com/) As a rule of thumb, I would pay about half the price for a raw coin as I would for a slabbed coin in similar condition. Note: PCGS and NGC will NOT grade cleaned coins. They will still charge you for the evaluation, but it won't come back in a slab. ANACS will grade cleaned coins, but it will note that the coins are cleaned on the slab, and you will only get a fraction of the price you would for the same coin if it wasn't cleaned.
Once you have determined rough values of your coins, you can decide how to proceed. Ebay has a vibrant marketplace, and there is also a local company called Teletrade (
http://www.teletrade.com) that will sell coins on consignment. Of course, you can always go through coin dealers, or place ads on places like Craigslist.
Also, depending on what you have, I may be interested in buying a few coins.