I for one would never pay for development software at home. I use VS2008 with ReSharper at work and I love it for what we do there. However I have chosen to abandon .NET and microsoft altogether for my home projects. I'm not going to get into the whole linux/c/java/open source vs. microsoft discussion here, but I would not pay upwards of 500 EUR for development software, It's as easy as that.
If I did have to or wanted to do .NET code at home I would certainly go with one of the free alternatives such as VS Express and NUnit. I have colleagues that do, and are reasonably happy with it. I'm sure I would miss some of the functionality and full integration though...
As for the ownership of code, I'm aware of the practise with companies claiming ownership af all code written while employed, however I find this unacceptable, and luckily it is not the normal practise where I live and work.
EDIT: When I was a student I had the option of getting Microsoft software free or very cheap from the MSDN Accademic Alliance and took advantage of this several times. I don't remember them having vs2008 however and I can't check since I've lost (forgotten) my MSDNAA login. Often the software availlable there is an older version than the current availlable release. Still... it's a very good deal and a great initiative from Microsoft.
EDIT: For school kids and students the Microsoft Dreamspark program could provide Visual Studio 2008 SP1 (and other software: VS2005, SQL Server 2008 Developer, Win Server 2008) free of charge. You log on using your Windows Live ID and verify your student connection to see if you qualify for the service. I was not aware of this option but I just dowloaded it myself, completely free and legal :D
EDIT: As pc1oad1etter pointed out there may be restrictions on the Dreamspark license, non-commercial use etc. So if you plan to make monney on what you produce read the license greement carefully before you decide.