In all honesty.. its all relative. Yes the TOTAL $$ value of a machine in general has dropped, but  its the main stream titles that have fallen... top end will always be top end and the price seldom varies. Even our friend with the KISS machines must have realised by now that he aint gonna squeeze more than $6800 out of this title.. each that sells floats around this price give or take a couple of hundred.
Problem... and yes it was a problem a year or two back was that general population lost the value of the $.. many loaned against their house equity to buy plasma TVs.. surround sound theatres and even pinballs... gee you couldnt pick up a dogs breakfast for less than a grand.
Thats all gone.. silly money lending is a thing of the past and so general float cash dries up.... now Joe Bloggs realises that his $1 cost him $1.10 to buy... not the 50c it was and so as the money dries up, so does the general flow of the $$.
Your $1 is now pretty precious.. before it was Monopoly money.
Percentage wise of general cash.. id say pins still cost the same... actual number of $$.... yep, its down