I just received a battery operated speaker via eBay which was advertised as being loud. I find the sound no louder than the iPad's built-in speaker which is very good. Is it the speaker ($10)? Or is no external speaker hooked up to the headphone jack much louder. Thanks.

You just got a lemon. There are plenty of speakers that you can hook up to an iPad with louder sound. Depends on your budget. 10 bucks probably won't get you much better than what you've already bought.

For about $20 you can do somewhat better. I have a bunch of smallish portable speakers I bought at Target for about $20 that offer a slight boost, but enough to make the difference.

I have a Jawbone Jambox Bluetooth that sells for about $180 to $200, which I love. It also can be plugged in via headphone jack.

I have a (gifted) Bose that sells for about $300, but I actually like the Jawbone better.

Altec Lansing iM227 Orbit ipod Speaker

The Altec Lansing Orbit MP3 ,This portable speaker uses a standard headphone jack to connect to your music device, allowing you to effortlessly amplify your favorite tunes from virtually any iPhone, iPod, MP3 player, music-enabled mobile phone, or laptop. With balanced components delivering clear, distortion-free sound, the Orbit MP3 Lite is an ideal solution for broadcasting music on the go