Seems to be a "fair" price if you take into consideration what the average price is on www.amazon.co.uk using todays exchange rate for 

iphone 4S 16GB   £540.00 x 133 =  KSH 71,820

http://www.amazon.co.uk/Apple-iPhone-4S-16GB-Black/dp/B004LBOI20/ref=sr_1_1?ie=UTF8&qid=1327008099&sr=8-1

iphone 4S  32GB    £595 x 133 =  KSH 79,135

http://www.amazon.co.uk/Apple-iPhone-4S-32GB-Black/dp/B005VO7HNI/ref=sr_1_2?s=electronics&ie=UTF8&qid=1327008568&sr=1-2

For that amount of cash… You can get  a "HTC Wildfire S" for Ksh 30,000

http://www.safaricom.co.ke/index.php?id=1520

and a Samsung Galaxy tab for Ksh 45,000

http://www.safaricom.co.ke/index.php?id=1020

And have twice the amount of fun… with some spare cash left over for some "chips funga" :)