Cross,

It's you versus the bean counters. I can't tell you what to do, only what I'd do in the same situation.

For the low end scenario I would go for the minimum spec that I would accept, NOT the minimum spec that accounting will accept. If management want to shave things thereafter then it's their decision.

At the low end I'd start with a SQL Standard Edition server that has the capabilities to deal with the expected load, plus an appropriate RAID level (maybe 5) and the ability to shift database backups and log backups either to another server or offline backup media on a regular basis.

Once you've covered the "needs" with the low end spec, go for some of the "wants" such as RAID 10 for robustness plus performance, maybe SQL Enterprise Edition for some of those extras that you'll use every few months (indexed views, log shipping, etc).

At the high end, throw in the things that Finance will laugh at - clustered servers, failover servers with EE log shipping, SAN, blah blah.