Can I change my iphone of company? Is Iphone 4 AT&T GSM?

I want change it to spint, or cricket and what is the price?

Those are both CDMA networks which means it's impossible to change to them. If your phone was unlocked you could switch to T-Mobile or another GSM carrier.

You can unlock your Iphone and use T-Mobile.

You could also use prepaid Net10 or Straight Talk. Net10 unlimited talk, text and 2GB of web with 30 service days for $50. Straight Talk unlimited talk, text and 2GB of web with 30 service days for $45.
You will have to buy a sim card from either Straight Talk or Net10 for $15. Then a unlimited plan. You will not have to unlock your AT&T phone to use Net10 or Straight Talk.