I would compare your hosting needs to what WordPress VIP Hosting provides for a flat rate of $500 per month with a $1,500 set up fee.
Here is what they provide for that amount:
- Your site running on the WordPress.com grid (over 1,200 servers in three data centers)
- Unlimited space and bandwidth
- 24/7 IT support
- Content Delivery Network and hourly backups
- Enterprise-level Akismet spam protection
- Optimization and security feedback on your site’s theme for a faster and more secure site
- Integration with WordPress.com features like Blogs of the Day, My Comments, Tag Surfer, and Gravatars
- Promotion of your new blogs on our Publisher Blog
- Sitemap and News Sitemap for better search engine and Google News exposure
- People logged in to WordPress.com will be logged in on your domain, making it easier for them to comment on your blog