Here in Singapore, our 3 service providers keep prices the same as their competitors, not much wiggle room.

For Mobile Plans:
12GB data 3.5G 7.2Mbps HSDPA + free incoming calls + 100min outgoing calls + 500 texts = US$25-27.

If you exceed the 12GB data, you pay an additional US$3 per 100MB. Additional charges are capped at US$22-24, whereupon you get unlimited data bandwidth.

fairly decent prices, but nothing compared to Hongkong where you can get 100Mbps unlimited broadband fixed lines for less than US$20 a month