Gray Card Recommendations?

[builttospill]

I need a gray card, and I don't want to pay a lot of money for it.  Can anyone recommend a good one?  Also what makes a good card good?  I've read about white cards that are 18 percent gray, and I've read about gray cards that reflect 18 percent light.  What does all this mean?  I just want a card (or other recommendation) to set my white balance on my digital camera (K10D).  Thanks for the help.

[Aliaksandr]

I use #4964 supplied by this guys: http://fotowand.de/ 

Site is quite awkward, but I like the card.

[Syates]

Why do you want to spend money on something that you can make yourself? Just create a document in Word or similar, draw a rectangle with the desired dimensions, fill with 18% grey (RGB 128, 128, 128 or #808080), print and presto! Your own custom size grey card for next to nothing ;-) ANd the trick with the hand was no joke, when not having a grey card at hand (pun intended ;-) the inside of your hand is a pretty good replacement. SY

[builttospill]

So that's not a bad idea to print my own, but what printer do you use?  Laser or ink-jet?  What about paper type and brightness?  Standard office paper is not very bright, I believe I have some 95 brightness HP paper, or would you use photo paper?  Thanks.

[Syates]

I use our normal office printer (inkjet/ Epson Stylus DX 4050) and white 160g paper (called "card" paper in the UK) I think the most important thing is not to use any glossy/ shining/ reflective paper. Hope that helps, SY

[builttospill]

OK, now that I'm ready to manually set the white balance in my camera, I have just a few more questions if you don't mind:

Do you use your gray cards for post-processing to adjust a batch of photos in PS, etc.?  Or do you use it to set the white balance before you shoot the batch?

If you use the gray card to set the white balance before a shoot, why not use a white card instead?  Or a white object in the photo?  What is the difference (pros and cons) between a white card and a gray card used before the shot?

Thanks for your suggestions so far.  I hope everyone doesn't mind me asking a lot of questions.  I've read quite a bit about adjusting white balance and no where have I found an article discussing advantages and limitations of each method.  As I'm not a fan of post-processing it seems I'm leaning toward getting the right white balance before I take the picture.  I hope a discussion here gives me some more ideas.

[Syates]

Hmpf, white card or white object I use to set the white balance when not shooting raw (what I prefer to do) and grey card I use to check/ set manual exposure. Do I have confused you now? Sorry, SY