It is going to cost an absolute fortune. Don't know much about helicopter licenses but I think you need to do the IR in a twin which means turbine and loads of cash
That's absolutely not true. I don't know about helo licenses either, but I do the conversion route for airplane tickets and it pays off easily.
Paid 25k pounds in the US for a CPL(A) ME IR, the same would cost me 50-60k pounds in Europe.
Go figure.... lotsa cash to spend on a conversion.