There are tons of creatine products out there, that range from straight creatine to creatine blends (such as Creatine with protein, or creatine with glutamine).
I recommend to use a product from a respected and technically advanced company.
Its like buying a car you don't buy a ford fiesta or a hyundai just because they are cheaper, you buy something that is quality even though it might be slightly more.
Remember this is something your putting in your body because you want it to perform so you want something that has manufacturing quality. I recommend products from Universal, Dymatize, BSN, EAS, etc.
A previous post talking about Creaform or CM is talking about the german creatine that is so pure it's patented and is used by companies like Universal and I think Dymatize, as well as a number of others.
Also someone was talking about the price, the price really depends on where you buy the product and the type of product you buy.
For example I buy EAS Phosphagen for $12.99 and Cell Tech (6.7lbs i think) for like $49.
also the universal stuff is like $20
I buy online because its cheaper, you can get 20% - 50%off retail price for the same product you can get in any sports nutrition store. Plus the place I buy from online has about 5 or 6 brands of creatine in multiple flavors and 8 or 9 types of creatine, including Kre-Alkalyn, liquid creatine, creatine with protein, creatine with glutamine, Creatine ethyl ester, and more.