Though this topic present over different forums with different confusing discussion but I couldn’t find any instance of it present over here at StackOverflow and it could be
You can still use the Windows Phone 7 emulator, but you will have to upgrade to a PC with a better processor to run the Windows Phone 8 emulator. The Windows Phone 8 emulator runs much better than the Windows Phone 7 emulator, so that is one positive of upgrading.
I bought an Acer Aspire V5-571 with an i5 and 6GB of RAM for $500 after tax to get SLAT support. With Black Friday deals coming, you can probably find something even cheaper.
If you can't afford a new PC or Windows Phone, you can still develop your app and have someone test it for you. That is definitely not an ideal solution, but it could hold you over in the short term.