@Doctor Who: I don't know about cheap / free versions of VMWare. I'm using the Mac version and have kept it updated ... I think I purchased it for $50? Obviously, having an MSDN license is part of this equation, too, or at least having access to the Windows OS you need, VS, SQL Server, etc.
Obviously, if you have an MSDN license ... or more specifically a Windows 2012 license, you already have access to Hyper-V.
Of course, if you have an MSDN license (perhaps your company purchased one for you) then you might think about running VMs on Azure for (essentially) free -- you get Azure credits ... $50 / month at a minimum. I've been playing around with Azure VMs for the past week ... it's really awesome. They even have VMs that are preconfigured with Visual Studio 2013 (Ultimate) Preview ... I haven't tried Phone development on an AZURE VM but in general, you could create a dozen VMs with various configurations, save them off, then spin up a copy when you have a new project and only pay for the time it's running. You just use Remote Desktop ... so I guess a good internet connection would be valuable, too. Admittedly, I haven't gone quite this far for my personal workflow, but it's the next step from what I'm doing right now.
Heck, running a quad core with 7 GB ram (Large instance) and Visual Studio 2013 ULTIMATE would only cost about $2.88 for an 8 hour day:
... no new hardware or software to buy. Yeah, ok, that's like $57.60 **IF** you keep one running 8 hours a day, Monday through Friday, for an entire month. I rarely get to code that much. So, .36 / hour ... that's a pretty good "rental fee" if you ask me.
(While I was writing this reply, I tried this out ... I have a pretty fast internet connection through Verizon Fios with 83 mbps down / 34 mbps up ... even so, there's a tiny lag when you type, but other than that, a gratifying experience. The whole setup took 10 minutes from login to the Azure portal to the point where I wrote a Hello World ASP.NET app).