I'm lucky and get to fly both for a living. Check out the life of parts on a helo and see just how many are lifed which aren't even fitted to a fixed wing, then take a look at insurance costs, regular training, fuel (not so much a carbon footprint, more a carbon stamp). I've only flown a very limited time in a Robinson (a few minutes in the last 10 000 helicopter hours) but £ 150 000 seems incredibly cheap, the Robinson website quotes £ 168 000 for a basic R22 Beta, so a day VFR VERY basic aircraft is still a fair chunk of cash, while a new 172 is a very well equipped machine.
The fixed and rotary types I currently fly work out around the same price an hour to fly, approx. £ 2 600, both are twin engine, full IFR, one goes about 150nm in an hour, one about 500nm, both are highly capable, but my Condor at £ 85 per hour is just so much more fun, and all mine.
People often ask me which helicopter I'd buy give a chance and the answer is none of them, unless you are lucky enough to hold an ATPLH/IR you can never get the use you can get out of a fixed wing (no single engine helicopter is cleared for any type of IFR/IMC, and twins are mind bendingly expensive). If you do a PPL/H and hire rather than buy you will often find that hirers ban PPL's from landing off airfields to protect their income and investment thereby negating the value of the helicopter anyway. Finally a lot of people don't realise that legislation actually bans single engine helicopters from landing at a lot of sites without specific CAA approvals for the pilot. Many ignore it, some don't know about it and just go, but in the event of an accident/incident they may find themselves in front of a judge without much in the way of a defense.
SND