how much is a 4gb micro sd cell phone memory card?

It all depends on where you buy this memory card from. I have come across a variety of sites that do sell a 4gb micro phone memory card for good prices too.

I have listed a few for you below that not only comes with the card but with sd adapter as well for low price.

FEATURES:

• The right solution for your phone 
  Eliminates the confusion in determining which card fits your phone with this flexible memory kit
• Do more with your phone 
  Take more photos, listen to more music, work on more emails, and more – just add more memory to your phone
• Easily transfer among devices 
  Use your extended memory capabilities to transfer your images, music,and data between your phone and SD flash memory-enabled device,regardless of the SD format 
• Easy migration 
  Use your memory to make migration to new phones easy through transferring your personal information
• Easy side-loading 
  On computers with full SD slots, you can side-load digital content by using the included SD adapter