I got a mix of 4u custom built boxes and a few mini servers using hacked up Shuttle XPC's. The one that runs this site is an oldie but goodie.
It has 4 first gen Xeon 1GHz slot 1 processors with 32 gigs of ram in a 4u case on an Intel motherboard. It has an Adaptec scsi controller, running 12 32gig IBM drives. 4 internal and 8 in an external enclosure.
It was the first server I put online 12 years ago and it's been up with the exception of OS reloads for the whole time. It's a workhorse and at the time cost over $10K to build. I would put it's performance up against any of the top of line servers of today.