Act like Google?
"Act like Google, buying commodity computers and relying on standard open system configurations" the second part may be practical (at least for servers), but the first part?
Google are one of the top 5 PC manufacturers (they just don't sell the things), so they have the scale to make this clever idea work. Their specialist computing requirements enable them to make use of massive parallelism on huge numbers of low-cost (relatively) low-performance computers.
For organisations that use a significantly smaller number of PCs (and that's practically everyone except the US government), this will be about as cost-effective as homebrewing your own PC. Dell can get a much better price on semi-conductor parts than you can, get them assembled offshore for a dollar a day and ship them around the world in bulk.
Buying computers or other IT kit purely on price is asinine anyway. Most of the cost of ownership comes in the support costs.
Remember: "Linux is only free if your time is worthless".