I'm going thorough this process now.
First of all, for low-timers (under 1500h) 14 ATPL subjects. Hard, but doable and not very expensive compared to the rest: from about 1000 to 3000 eur (depends on a school).
I assume that with that FAA license you already have above 200h TT and a 300nm+ solo XC.
NVFR: 5 hours training in a single-engine (SE) airplane, from 2 days.
IR/SE conversion - if you have 50h PIC IFR (not FAA PIC though - it should be without a CFI in the airplane), no min hours requirement. Just some training in the EU airspace to prepare for a skill test. From 1 week.
CPL: 15 hours training in a flight school (ATO) and a skill test. From 1 week.
ME: 6 hours training and a skill test. From 2 days.
ME/IR: 5 hours training and a skill test. From 2 days.
Total price highly depends on flight hours. ME hour price is very high in Europe, and even those 11 hours mean a lot of money (hour price is from about 400 eur). SE hour price is from about 150 eur. In overall it will be about 10-15k euro.
That's it for piston airplane ratings. After all of this it will be unrestricted EASA license with SEP/IR and MEP/IR, most probably with PBN.