Apple’s Bumper cases for the iPhone 4 are now shipping. The accessories come in blue, green, orange, pink and white, they are made of rubber and molded plastic. Bumpers are available at Apple’s online store and at Apple Stores nationwide. Please note: these cases will only work with the iPhone 4 and not with earlier iPhone models.

Since Apple’s admission last week that adding a case to an iPhone 4 could improve its signal quality, Bumpers will likely become a popular choice among iPhone 4 users. With Bumpers priced at a premium $29.00 plus shipping, however, it might be worth checking out some cheaper third-party cases that are also available.

Best Buy has a great selection of ifrogz cases for the iPhone 4 and they are in stock now. When I purchased my new iPhone 4 last week, I purchased this blue ifrogz case. They also come in iron, red, pink and green with prices starting at $24.99.

BoxWave’s $19.99 Pure Crystal Slip rubber covers look very similar to Bumpers. These are advertised as washable and tear-resistant, they are available in frosted clear, smoke grey, cosmo pink, and azure blue. BoxWave’s $19.99 Pure Crystal Slip rubber covers look very similar to Bumpers, but at two-thirds the cost.

Finally, Case-Mate has a cool line of Gelli cases for the iPhone 4 made of lightweight thermoplastic and they are said to be impact and scratch resistant. Priced at $19.99, Gelli cases come in patterned designs, the colors are: tomato, aurora, clear, grey, pink, and teal blue.

Each of the cases mentioned come with a screen protector kit, which is nothing more than a piece of plastic that can be affixed to the iPhone 4′s screen. While I personally find these “kits” annoying (the plastic bubbles up), others may like them.

Be sure to check out these iPhone 4 cases. They are great alternatives to the pricey Apple Bumpers, and they are shipping now.

How do you protect your iPhone 4? Please let us know in the comments box below.