Short of building a dedicated VM box with multiple instances for AD, SQL Server, and one or more SharePoint servers, and then securing a static IP account for real-world work and internet connectivity, CloudShare provides a reasonable alternative.
I’ve recently set up a CloudShare account (they are not compensating me for this plug…) to do some prototyping. They offer several plans, including a ‘pay by the drink’ plan where you are charged for memory usage (GB/hour) only when the virtual servers are running. You can connect to the servers through RDP, PowerShell, and a browser interface. The experience is best when you connect via RDP – much like being connected to a server within a closed environment. If you are comfortable with typical VPN, then you will be comfortable with this mode.
I’ll elaborate more after I’ve used it for a while and get a feel for how much it costs to use.