Well, unless my web-application includes testing gestures, I would not be so concerned about buying a device lab. It just seems so unreasonably expensive. If the rendering of my website across browsers or devices is my concern area then I would rather pick between Emulator vs Simulator. They can provide me good enough results if responsiveness or cross browser compatibility is my concern. I am not saying that they won’t be any difference between Emulator & Simulator, vs Device labs. However, the difference would be very marginal compared to the difference of cost. As you can see, mobile simulation and emulation is the best method today to test your website with a couple of advantages:
1. Cheaper: Mobile simulation and emulation come at a very cheap cost. The cloud-based technologies in cross browser testing that use emulators on their real systems are completely dedicated to this sole purpose. While renting out device labs is almost the same time that it is for the cloud (since device labs are also working on the cloud) but the cost of device labs is huge as compared to online cloud-based emulator technologies. Moreover, the amount of time that you cut by opting for mobile emulation is so high that it is incomparable.
2. More Scalable Approach: If you are going to use the conventional methods, the cost of that will burn your pockets. For testing just one website you might have to spend a lot of money and endless hours. This is never desired. Moreover, even though you purchase some devices, you can never compare them with the ones you can use through mobile emulation. Using an emulator or using cloud-based services, mobile emulators helps you test on a wide range of devices. You just have to select the device with a single-click. The software will automatically emulate the device without any extra setup or cost. Since some devices have some constraints, using cloud-based emulators ease out the process.