Netherlands Rail Fares - Why Advance purchase??

Is there any price advantage in advance purchase of train fares in the
Netherlands, or is it simply better to buy a ticket at a station and go
immediatly seeing that to most destinations trains run about every hour?
The various internet sites flogging tickets seem to suggest that advance
purchase is cheaper, and there are so many "resellers" taht it seems hard to
find the "real" Dutch rail fares amongst all the commercial ticket reseller
hype like RailEurope trying to sell tickets to tourists.

I don't want to advance purchase, because I will be wanting to go to various
places to buy a boat in Holland, and won't know exactly where next till it
happens.

Is there an internet site to get good factual advice on rail travel in
Holland, free of all the confusing ticket reseller hype and commercial crap
one commonly finds.

Perhaps hiring a car woul be much cheaper for two people travelling
together, as the one way fare from Amsterdam to Sneek quoted on RailEurope
website was A$56, so A$112 for two, and you can hire a car for several days
for less than that. I have driven a lot (50,000Kms) in Europe so experience
is not an issue.