It's not that easy
Remember it's usually not the hardware which fails, although that's where it's easiest to throw money. The biggest components of service recovery are problem determination and application restore. I don't think I've ever seen application restoration following failure as a requirement during application package selection, that always is viewed as an infrastructure problem or a bolt on.
This is in terms of operational failure, when you talk 'DR' then it adds organisational reaction times to the mix. I've only once worked with an organisation (a global bank) which actually could cope with a disaster hitting it's datacentre.
I've come round to the view that for most businesses, building a bulletproof main environment is more worthwhile than trying to provide a cut price DR environment.
A lot of companies lease a virtualised DR centre > shipping their data and planning to call down capacity from a server farm if they need to invoke DR. I'd love to know how the DC provider calculates capacity and whether they refuse customers who are too close geographically to each other and likely to suffer from the same disasters.
Buy me a pint and I'll keep talking all day about this.