Well, hopefully a VM will be enough for compiling and tht it will work with b4i. For testing, I think that inevitably you need an iphone and/or an ipad device (but you can get good deals online for older devices).
I think the oldest you should aim for is a 4S - which is the oldest device that will accept iOS 8. Although I'm not sure how quickly 4S phones run iOS8... but it should allow testing at least.