^^ you need to look up performance stats on this. The number of transactions a SSD based server can perform over a HDD is in the region 10-100x. That means, depending on application, you could save yourself up to 100 servers. Now that is space saving. Energy saving. And $ saving. Bigtime.
Remember, SSD is NOT for filestorage or media archive, it is for OS, swap, and small and medium sized database "transaction" based processing. If you are running, eg. an ERP solution, LDAP, webserver, etc. this is ideal.
What do you save? (on an example of ONE SSD server replaces 11 HDD servers)
1./ 10x physical server cost, could be $3000 per server = approx $30000
2./ 10x copies of Windows Server, application software, antivirus, etc. cost say $1500 = approx = $15000
3./ 10x annual electricity cost, say $300 = approx = $3000
4./ 10x installation time and maintenance time, incl. updating etc. say $500 per commission = approx = $5000
5./ 10x space utilisation for the server rack. If you have a big service centre this adds up to a lot of sq. foot and therefore less rent. Calc=0 for just one rack, but if you do this across a datacentre, the numbers may be big.
So I can see that (again depending on application/situtation) installing ONE SSD server could save you approx $50000 compared to HDD servers with the same transaction capability.
And the cost of doing this? $500 for the SSD, = 1%.
Another way to look at this, is, again depending on load, you could decommission 10 servers and replace the HDDs in one of them with a SSD. You pay for the SSD within a year of saved electric bills, plus you have freed up a lot of space, to be repurposed. For an IT company, it means you increase your service capacity without having to lease new buildings.