No its not at all.
An 8 core system for 2800 dollars is pretty cheap from where I am standing, especially in comparison to any other OEM, or indeed DIY.
Yeah the Mac Pro has always been value for what you get. I actually just had a look at component prices and found the following interesting. The rough numbers were before I added the total up! Obviously you can build a better/cheaper system using Skulltrail and overclocking or a socket 775 or i7 system if you don't need 8 cores.
Intel E5462 x 2 - $1,662.98 (buy.com)
Super Micro X7DWA-N - $419.99 (buy.com)
2x1GB 800MHz FB-DIMM - $71.99 (OWC)
256MB 2600XT - $49.99 (newegg)
320GB Drive - $49.99 (newegg)
Optical Drive - ~$25
Silverstone Temjin TJ05S-X Case - $159.99 (xoxide.com)
1000W PSU - ~$200
Mouse - ~$15
Keyboard - ~$15
OSX Leopard - $129
Total: $2798.93