For the official fees page see herefinancially how much does it cost to apply 150 programs or 40 programs
can an IMG take residency in university programs and how to increase this chanceFor the official fees page see here
150 Programs cost $3305
40 Programs cost $555
If one applies to programs in several different specialties, are the PDs able to see this? If so, surely you would be shooting yourself in the foot as they would think you aren't clear on what you really want to do?This question is very difficult to answer. There are many factors that can play role in your likelihood of getting an interview and subsequently a match.
Have a look here http://www.usmle-forums.com/residency-match-recommended-threads/40-matching-filters.html
If your profile is strong then it might be few (3-5) interviews enough for you to get a match and it might be few applications (10-20) to get you these interviews.
If your profile is weak (like being an IMG, old graduate, low scores, no USCE, no publications, no connections, no US LoRs ....etc) then I'd say apply to as many programs as financially possible and even apply to other specialties like if your are looking for IM then apply for FM and even psychiatry if you can.