If you take a look at http://prepaidgsm.net, you’ll see the reason for PortMoresby’s recommendation. It’s not the cost of the phone, it’s the cost of every minute, often many times that of a local SIM.
For example, the Mobal SIM comes with a rate for Morocco of $1.50 a minute outgoing and $1.50 a minute incoming. Meditel, one of the Moroccan carriers, charges (depending on plan) about 10c a minute up to 40c a minute, and no charge for incoming. Mobal will sell you data at $28.99 for ONE megabyte; Meditel will sell you a month of unlimited for under $25.
DO NOT ever think of dealing with one of these international phone rental companies; they are strictly for corporations that don’t care what they pay.
Oh, and another thing: your number from Mobal will be a UK number. If the friend also has a Mobal phone, calls between them will be $1.95 minute, not the $1.50 rate for local calls. And any Moroccan phone that calls the Mobal phone will be charged for a long-distance call to Britain.