You don't need a ROM if you are running AROS. See AROS.org about a Windows-hosted install of AROS. You won't have access to the chipset emulation under AROS though.
-edit-
You can get the AmigaForever Value edition with Kickstart 1.3 for only $9.95 if you don't need a newer Kickstart. It won't work with AmigaE though, since AmigaE uses Kickstart 2.x or newer. PortablE is a frontend for C++ or AmigaE so it won't help you much with that Kickstart either.
