Just pay attention from wirefly
http://www.wirefly.com/about/purchaseterms/ :
Delivering on this promise means that you must agree to maintain your agreement for a minimum of 6 months after activation. Deactivating your phone, or downgrading features or the rate plan, may lead to additional charges.
When you sign up for wireless carrier service through Wirefly, we discount your phone purchase price by an Equipment Discount amount ranging from $200 to $300. By ordering through Wirefly, you agree to repay this discount if, during the 181 days after your new equipment is activated, if you:
Fail to pay your balance due to your carrier each month
Disconnect this line of service
Transfer this equipment to another line of service
Change your carrier service rate plan to a lower monthly service rate plan
Deactivate the email/data feature if one was required at the point of purchase
Transfer/port an existing phone number from another account if this is a new line of service
Replace an existing account with this account if this is a new line of service
Return or exchange your phone and it is not in its original, new condition with no more than 30 minutes of usage
If you break any of these contract provisions, except as a result of a documented service quality issue related to the carrier service, you authorize us to charge your credit card in repayment of the Equipment Discount
Yeah...
Also, they do not mention a particular early termination fee - I think its $400, or it used to be.
Just beware, these are sticky rules.