Every time I consider buying a server, I come to the conclusion that I'm better off keeping a VPS plan. I pay $149/month at hostmysite.com and that includes:
- 1GB RAM
- Bandwidth
- Backups
- 22 GB disk (on RAID)
- Monitoring
- Server management and patching
- SQL Server Workgroup
- etc.....
I use about 775GB RAM for the OS, SQL Server and 2 DNN installs.
When you look at buying a server also factor in the bandwidth, software and services. As mentioned above, Windows is $800 and SQL Server Workgroup is thousands (I know Express is free if it has all the features you want). I personally want to spend time building the sites, not being a server admin so maybe that's just me but I like knowing someone else is handling the patches, monitoring, security setup, etc. I'm also on a high-end server with the VPS that would cost me thousands to buy on my own (fast CPU, RAID, etc).
MaximumASP.net now has a 1.5GB VPS for $99/month.
Just something to consider.