Even though you didn't say where it sells for $180 usd, I bet you are referring to some scam Chinese websites. Here is one we discussed in another thread:
PLEASE NOTE, a few weeks ago, Microsoft announced they have delayed to release Xbox 360 in China because of security/pirate concerns. If someone in China claims can sell you Xbox 360 at cheaper prices than Microsoft's cost, you'd better think twice before sending your money to them through Western Union.
Remember Xbox360 has an expensive multi-core PowerPC processor and a high-end ATI's GPU, it is a high-end PC, with the premium bundles, Microsoft doesn't make much money by selling it under $150 or $200.