If there's one thing I'd love to remove from the tech world, its podcast-studio-in-a-box kits. These tend to include an omnidirectional USB microphone, some monitoring headphones and some cheap (or free) audio-editing software. These DIY kits offer simple equipment to amateurs who, presumably, aren't familiar enough with audio production to pick up an omnidirectional microphone themselves and download a free program like Audacity to edit their voice.
My advice to potential podcast producers is this: if you can't put together a kit like this yourselves, you're not ready to be a podcaster yet. A badly produced podcast is simply difficult to listen to. If you've got loads to say but you can't put together a little podcasting kit, just stick to blogging. There's a reason it's a successful medium -- it's easy, it's free and it's accessible. Also, your own unique perspective on the world is far more easily discovered via Google if you publish text than if you publish an MP3.
Half the joy of being a hobbyist in the audio world comes from using equipment. You'll produce a much more professional sound (not to mention a potentially more popular podcast) if you put some effort into knowing why something sounds better. Do a little research into condenser microphones, read up on some simple and affordable mini-mixing desks (as these allow for creative expansion) and if you're really keen, sound-treat your recording space. You'll do all this for little more than you'd spend on a pre-built kit anyway.
I admit that to the absolute beginner, a USB microphone is attractive. But a tiny bit of effort will yield much more compelling creative content. If cost is a serious issue, look to Behringer -- it makes excellent hardware for a fraction of the cost of the competition. Bear all this in mind, and you'll stand out above other beginner podcasters.