BlueStacks don't offer Android Market apk, but we can find the apk from XDA forum. Download the zip file from this link:
After unzip apk files from the zip file, install the apk in the following order using the method showed here:
If you don't have any google account, you can use normal method (web browser on PC) to create one new account.
If you already have google account, you can use the same user name and password to login to Android Apps.
After login, it is just like browsing Android Market on Android phone. Find your apps and install and launch it. Do note that apps that installed through Android Market has to be launch from Android Market. I cannot find the apps appear on launcher of BlueStacks.
Android Market also require internet access no matter to launch the apps that already install. So there might be a problem if you are offline (not connected to internet all the time).
I also installed Amazon AppStore on BlueStacks, however the apps that I installed through Amazon AppStore seems like taking forever to load (a.k.a not running). Probably it is because the apps or Amazon AppStore, I have to check again.
Because of limitation of Android Market and Amazon AppStore, I still think installing apk directly is the best method.
Update (Jan 19, 2012): If you are plan to upgrade BlueStacks and if you want to preserve the icon arrangement after you edit the apps.json, make sure you back up the file before you run the upgrade.
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