Sorry for the lengthy post...
Here's my workings. The 44.05 deal for 16gb seems best for me........
mins/texts - (monthly price x contract period = total) + phone cost = total cost
18 months:
3GS 16GB
75/125 - (29.38 X 18 = 528.84) + 184.98 = 713.82
600/500 - (34.26 X 18 = 616.68) + 184.98 = 801.66
1200/500 - (44.05 X 18 = 729.90) + 87.11 = 817.01 <--------------- My best deal. £15 extra for double the mins every month. thats £15 extra on the total value, not per month
3000/500 - (73.41 X 18 = 1321.38) + 0 = 1321.38
3GS 32GB
75/125 - (29.38 X 18 = 528.84) + 274.23 = 803.07
600/500 - (34.26 X 18 = 616.68) + 274.23 = 890.91
1200/500 - (44.05 X 18 = 729.90) + 175.19 = 905.09
3000/500 - (73.41 X 18 = 1321.38) + 96.89 = 1418.27
24 Months:
3GS 16GB
600/500 - (34.26 X 24 = 822.24) + 87.11 = 909.35
1200/500 - (44.05 X 24 = 1057.20) + 0 = 1057.20
3000/500 - (73.41 X 24 = 1761.84) + 0 = 1761.84
3GS 32GB
600/500 - (34.26 X 24 = 822.24) + 175.19 = 997.43
1200/500 - (44.05 X 24 = 1057.20) + 96.89 = 1154.09
3000/500 - (73.41 X 24 = 1761.84) + 0 = 1761.84
There seems to be no real reason to go for 24 months which seems odd?
The unlimited text bundle is 132.12 for the 18 months, so add that to whatever figure your interested in if you need it.