[thelist] How to protect against downtime?

[Faust at LeeMarvin.com]

Project:
Create a e-commerce site to sell for three months up to an event.

Tools:
Last year's code for Coldfusion 4.5, SQL-Server 7, and IONGate (to
handle the transactions) can be reused.  A shared hosting environment
(CrystalTech, Verio, Media 3, InterMedia, etc..) with these or similar tools
will be used.  Dedicated hosting is probably too expensive for this
project.

Problem:
The site _cannot_ go down for any reason.  DRDoS attacks, DNS
hacking, and the like worry me about relying on a single host.

My crack at a solution:
Get two separate hosts.  One primary and the other as a mirror.  Update
both the primary and the mirror database for each transaction.  If the
primary goes down, switch the DNS to point to the mirror.

Does anyone have any suggestions?

Am I completely off my rocker?


TIA

Faust

"The cheapest and easiest way to become an influential man
 and be looked up to by the community at large, was to
 stand behind a bar, wear a cluster diamond pin, and sell
 whiskey. I am not sure, but the saloon-keeper held a
 shade higher rank than any other member of society. His
 opinion had weight."
- Mark Twain, Roughing It