Translation:She buys fabric in order to make a curtain.
Yes and no - it used to be a correct form, so most Swedes will have come across it in e.g. some older text or movies. It's also obviously very close to the correct form, so realising what's meant isn't a stretch. However, removing the för turns the whole thing into a garden path sentence, since hon köper tyg att .... med means "she buys fabric with which to ...", so when the sentence then doesn't end in a med, that might be a bit confusing.