re: Unlocked iPhone 5: Worth The Cost?
The discrepancy in carrier costs is even larger than you calculate. Your contract cost is at least $70 plus taxes which can add $20+ to your bill. Realistically, you would be hard pressed to find any person with a one-phone cell plan who is paying less than $100 a month, even with the most basic services. On the pre-paid side you are paying $30 a month and that includes the taxes. The real world difference in cost can be $70 a month or more, which means your off-contract iPhone will pay for itself in seven months or less.
The down-side is that you will not get LTE speeds. As good as HSPA+ is, for people who are tied to cellular data all day long, that 3G Plus will not be good enough. However, for those of us who spend most of our day on Wi-Fi, it is silly to not take advantage of the price difference.
As it relates to not being able to port your cell phone number - that does not have to be an issue. Port your phone number to Google Voice and then your number will travel with you to any device or carrier you pick. It gives enormous freedom and adds some other features (number following you to multiple devices, text conversion of voicemails, VoIP calling, etc) that are quite useful.
Finally, the market for top unlocked devices is getting better every day. Many of the hottest cell phones are available without a contract today and it is nice the iPhone 5 finally joined the party. I think the best options for the money today are the Nexus 4 and the Note 2, but the iPhone 5 is certainly a great choice.