If you haven't programmed anything yet, I would definitely scrap windows + asp, as you'll really be limiting the kind of people who can work on that going forward, as well as increasing your costs in a number of areas.
If the site is already programmed, then within your budget I would look for a hybrid server / vps if you care about quality. You'll be able to get a good quality vps on a good network with good uptime, probably with management (if you need it) and backups etc, without too much trouble for $100 or less. At the same time, a dedicated server for $100 or less, with windows on it, is going to be a bit of a challenge in general, especially if you have any particular requirements such as location, network quality, etc.