What is your best/worth photo purchase?

The worst is the 50 f/1.8 lens. I didn't get much use out of it before moving up to the 50 f/1.4. But it was cheap.

The best are the six BP511 1800mAh batteries I bought for $60-something from SterlingTek for my 300D. They are much better and cheaper than the Canon batteries and I now use them in my 5D.

Coming into this thread a bit late...

My worst purchase was the Canon S9000 printer. It prints great, don't get me wrong, but I rarely print a 8x10, let alone 13x19.

The best purchase was my Lowepro Off Trail 1 camera bag. I've had this for several years and it's been great to tote around my camera/lens in. I can add/take off accessory bags as I see fit, which is a big plus. Plus it's not bulky and the waist strap makes it much easier for me to move around instead of having it on my shoulder/back and having to reach around for the camera.

A tripod with a remote! invaluble for my shots at night
Worst... maybe my bag, i dont like how it has just the one strap, kinda hurts with the weight of all my stuff

The ones I perhaps regret are the two lenses I bought when I got my first DSLR, the 10D. I was anxious to get something, anything really and I bought on price point alone. I got the original 24-85 and 100-300. They were not real bad but not what I had hoped for. My son uses them now and he does just fine, he is not all gung ho about photography and they do just fine for him. Since then, I have bought allot and I don't regret any of it. I tend to do allot of research now before I hit the complete transaction button.

My best purchase is hard to say just one thing. I love all of my long lenses but out of them probably the 300 f/2.8 L IS is my favorite. I've got many little gizmos and gadgets that I wouldn't want to do without, rocket blower, better beamer, plamps, the list goes on. I use everything that I have.

Well, I've got the 350D, which I love, and after seeing the 400D, I'm OK with not having the latest and greatest model. Sure, a 5D would be nice, but the 350D is enough camera for me now. As for lenses, I started with a 50mm f/1.4, and I quickly learned how much using a flash just sucks (more on that later). After the 50mm f/1.4, I picked up the 200mm f/2.8 since I wanted to get some pictures at my dad's graduation. The 50mm is an awesome lens, but if you need reach, it isn't the lens for the job. But the flip side is that if I want to take a picture of something large, the 50mm isn't too great there either if I can't take a few dozen paces back. So I picked up the 15mm f/2.8 fisheye and created an automator workflow to defish images in seconds. No need to open an image editing application. I keep all of this in a LowePro Slingshot 200AW, which I am a big fan of.

What do I regret? My 430EX. I've got lots of fast glass, but I fear one day it won't be fast enough, so I keep this around. I should have waited for one to shop up used at a good price, but didn't.