Yes, the retail version of Windows is expensive. It's not a big deal when you buy a new computer, because that OEM copy is cheap and you hardly notice. But if you are a computer enthusiast and have a few PC's at home, staying legit and sticking to Microsoft can get expensive.
1). Get an OEM copy. You save money, but technically it's tied to the computer...thus you cannot move it later to another PC.
2). Get a technet subscription. These are $200 for the first year and $149 a year to renew. You get copies of a ton of MS software and multiple license keys. Thus, you can download and run whatever you want, including Office. It's intended for IT professionals and the licensing says it's for "evaluation purposes". But a call to MS confirms that running it at home on home computers as a tech enthusiast is ok. If you don't renew, you won't have access to new downloads or new keys, but your existing keys keep working.