If you want, centOS is basically RHEL except without the exclusive support (that costs you revenue). The same team that develops RHEL also helps develop centOS. The main pro for debian that I can think of is compatibility and it's package system or .deb, otherwise centOS is more provider-centric with some handy server features out of the box.
(chassis will cost you around 200-1k $) and blades around 200-400$ each.
(together you should be getting something like this http://www.ebay.com/itm/86773XU-IBM-BladeCenter-E-chassis-14-IBM-HS21-2-x-13N2285-CISCO-Gigabit-Switch-/380506307680?pt=COMP_EN_Servers&hash=item5897f17c60 )
NAS Storage something expensive.
Software:
Vmware VShpere and create a cloud of those.
Other: Network gateway i recommend getting fibre connection to internet...
Then you can host a lot of servers without that big amount of power draw and building racks and big ac's to cool them down... This is how most of better companies do the hosting. (OVH in europe, and better ones in USA like americaneagle)