What the Heck?

I'm seriously thinking about taking up Voicestream/T-Mobile on their GPRS data service. $40/month for 20MB doesn't seem so bad, especially with Pocket PC Phone Edition set to be as data frugal as possible. Pity those Handspring Treo 300 customers stuck with Sprint's PCS Vision, their version of the CDMA 1xRTT standard. Sprint wants $45/month for 2MB, with about $20/MB after that. Anyone care to explain why the CDMA packet data network is ten times more expensive than the GSM packet data network?