I Need Some Info....

Welcome to forum! I would first stick to buying from sellers who are in the Ancient Coin business. Checking prior feedback is one way to determine if the seller is a crook or not. I learned if the price seems too good to be true, sometimes it is. Proper identification and forums like this one can help with any potential purchase. Many members here are extremely knowledgeable in Ancient Coins so if you post any information, someone is bound to answer.

I prefer to buy from actual dealers who also list on ebay. Another thing you can do is look through various databases for fake coins and sellers to avoid. https://www.forumancientcoins.com has a fake coin report section which lists thousands of fakes that were sold on ebay.

First of all,

As for ancient coins, many are quite common while others are very rare. Run-of-the-mill bronze coins are constantly found in large hoards throughout Europe in quantities of hundreds or thousands. Uncleaned, unidentified coins tend to be the cheapest and can be purchased in quantities for a dollar or so each. And of course, cleaned and identified coins do bring more money but they can still be affordable enough that a kid could start a basic ancient collection with allowance money. Once you get outside of the common bronze issues, the gold and silver ancients can quickly climb in value.

does anybody recommend any good books on the subject?

I strongly recommend against ebay as a place to begin buying ancient coins. ebay tends to attract more than it's fair share of "sharks" selling counterfeit ancient coins; it's not a safe place to learn to swim.

But if you must go the ebay route, I'd first check to see if the seller you're planning to buy from is on the FORVM blacklist of known and unrepentant sellers of fakes, which Spider mentioned above. If you find the seller's ebay ID listed there, stay well away from their coins.

I must confess to getting hooked on ancient, uncleaned Romans. I know that when I'm holding one, I have a direct link to someone who lived almost 2,000 years ago and buried the coin for whatever reason, including hiding it until he could return from battle ... but never did. I recommend "oldcoinman" on ebay if you want to get into "cleaners", and I would suggest avoiding any seller who proclaims "gold found!" in his promo copy. (I did find one billon and two silver-washed coins in the lots I bought from oldcoinman, but you'll never find him suggesting that any of the coins he'll send will be anything but base metal.)

You can't go wrong if you buy from Frovm Ancients Coins. There have been several threads on how to clean ancients posted here.