Petroleum ether is an oil fraction, a mix of relatively simple hydrocarbons such as hexane. There are many mixes like this that are very similar, that can just be slightly different kinds of oil fractions with lower or higher boiling points and other properties.
Naphtha is such a virtually identical solvent that you can substitute, it can probably be bought in hardware stores as coleman fuel or something like that, or white spirit. It's very common with plenty of uses, and not illegal or watched. Just google around a little on these names I mentioned and you will see that it's nothing special and abundantly available. Find it on your own after that.
Good luck with whatever you are planning with it, but unfortunately beyond this bit of info Bluelight is a harm reduction forum about drugs - so your question is not really appropriate enough to continue.
