I'm currently using Cingular (ftw!) with a family plan with a $20 dollar plan for unlimited texting.
I want to get a sidekick just for the unlimited texting/data plan with TMobile but I'm so lost

I was offered a $50 after rebate deal for the Sidekick LX from the dealer at the mall if I get the myFaves 300 (300 minutes for $39.99 with unlimited nights&weekends&5numbers) with a 1 year contract. But then I would have to pay another $20 for the unlimited data plan. Which is like, $60 a month, 12 months a year.
But I don't really like the plan because T MOBILE SUCKSSSSSS. I only want to get the SK for the data plan! (and plan to stay with cingular with my family plan)
I originally wanted to get the $50 Sidekick ID with a $30 unlimited SK data plan. But The Sidekick ID is discontinued! So I was thinking of buying a sidekick off ebay or something. But then how would I get the plan on the phone? Do I have to go to the dealer and ask for the plan or something? I'm so lost. I haven't used T-Mobile since 1999.

Can someone explain the steps for me activate my phone/get the plan from the dealer or something if I do get a SK online? Is the SK LX plan worth it? Does the Unlimited SK data plan need a 2 year contract?

TY

Sorry if I don't make any sense

Just buy a sidekick off of ebay and call T-Mobile customer service at 1-800-937-8997 to add the sidekick data plan in.
For more infos: Sidekick Data Plan
I think the sidekick LX is really nice, I'd get it if I have the chance. I'm using SK3 right now and I really love it. Imagine if it's SK LX, ^^.

You can buy just the Sidekick LX, but if you want it at a cheap price then you would have to sign a contract with a minutes plan. If you really want the sidekick with no minutes, then you'll have to buy it at full price or go to ebay, and call T-mobile to add the $30 sidekick plan. You will still have to be binded into a contract, I don't know how long though. You probably don't even need a contract, but I'm not 100% sure on the contract thing.

Btw, may I ask why you want to keep your phone(minutes) on At&t and then use T-mobile for data and messaging?

I ask because it would probably be a hassle to have two different numbers and having to tell all your friends and such. I would just recommend that you add Media Max unlimited service which is just $35 a month. I think it's worth the extra $5 since you wouldn't have to maintain two different numbers, but that's just me.