The "problem" with accessories for your iPad isn't their price or their rarity; actually, the real issue is that there's a whole deluge of choices for you to deal with. Not every keyboard, mouse, adapter, screen protector, and stylus is made equal, but those aren't the only picks you're faced with. It's the categories themselves that are dizzying.
You have iPad cases, anti-glare film, iPad armor, a USB power adapter with a sync cable, headphone splitter, USB splitter, batteries, galore, stereos, a radio you can connect to your iPad, an automobile charger with a USB connector so that you can charge up your iPad when you go to work, and a variety of other items that makes iPad accessory shopping such a joy to behold. In order to narrow down your iPad accessory choices, it's imperative that you cool down, take a breather, and realize the difference of what you want and what you need.
A Bluetooth keyboard, for example, is something that you need, especially if you're a news reporter or a blogger and you're tasked to write up stories on the fly. A DVD drive is another handy tool to have if you're looking to transform your portable tablet into a desktop computer when you're not "mobile".
Indeed, having a few luxuries doesn't hurt as long as you're fully aware that you don't need them and you should only splurge on them with disposable income. Ear buds are nice, but you can do better with Natural Wood ear buds in stereo (as opposed to plain-old ear buds in mono). You don't actually need to get ear buds that sound like you're in a movie theater while you're using your tablet, but if it makes you happy or it entertains you to have that (and you're not spending beyond your means), then go ahead and buy them.
That's the thing you need to keep in mind when it comes to iPad accessory shopping; separating the practical from the luxury items. Speaking of practical, you should get a cable kit for your tablet in case your USB splitters, mouse, keyboard, external hard drive, headphones, ear buds, and so forth are cramping up your space and making your iPad look like it's hooked on life support.
In terms of portability, the mini keyboard is better than the keyboard, while there are also speakerphones available that are car-mountable depending on whether or not you love to drive with your iPad. There's a motorcycle kit for iPad interphones as well.