To get phones at good prices, you're going to have to sign at least a one year contract with Cingular. The $29.99 and free prices and such they advertise (even the $130.00 phones) are with a contract.
If you're looking to buy a phone from your carrier without signing a contract, add at least $150 to the price you see on the website.
If you are an existing customer, you have to be eligible for an upgrade (check your account summary) on the phone line you want to buy the phone for. That way, you can sign a new contract, and buy the phone for a discounted price. They waive the activation fees and you only pay an $18.00 upgrade fee.
You can also get a mail-in rebate on some Cingular phones right now, but to be eligible for these you have to sign at least a one year contract. However, I've heard that the rebate center is stupid and that sometimes you can get the rebate with no contract. But I don't believe it.