I know what you mean. I recently bought a new board and am very happy with it. This new board will probably last me 20 years or so just like the old one. Interestingly, the bloke who bought the old one for a carton of beer uses it for light wind speed work (good on you Ben). I work on the idea that the gear you rode a couple of years ago is still good enough to ride today. I am not a GPS rider and only go out to enjoy myself. I can do that on old gear just as well as new gear. I do understand why good riders like the best gear, I am just not one of them. (Good rider or best gear)
The start-up cost of the sport can be expensive but once you are over that hurdle, if you look after your stuff it isn't too bad.
Shhh...if you talk the cashed-up 'glam' guys out of buying new, then the s/h market will increase in price for us that can't justify the cost of new gear (although s/h can be sometimes as costly!). 
I started 4 years ago and loved it badly. I have 4 boards now, 9 sails, a dozen fins, 2 booms, 6 masts. it looks exagerated, but i bought everything 2nd hand, good quality. I worked out that it cost me roughly $55 per week since i started. I think it is actually a great investment in fun, health and wellbeing, if you consider you could spend more if you were smoking, or gambling, or even for a night at the pub.
interesting concept
when and how does one "stop the shop" ?
one of the complaints with this sport is equipment - size , cost , space, etc
can buy used/2nd hand and keep things minimal
when is one satisfied ??
i use 4 boards, longboard, freeformula, large freeride and small freeride
with 4 sails , 6 fins, 3 masts, 2 booms, etc
over time it costs less than $100 per month
and total spent is about $8000 - which is not much if one says boards are around $2000 and sail + mast around $1000 NEW
the old stuff is still good stuff !!
i have Fanatic Ultra CAT longboard and BIC Techno Formula freeformula/94 cm wide
these are classics and serve me well
the freerides will be easier to replace used :-)
keep on rockin in the free world
freeride freemove freestyle freeformula etc etc
I love spending cash on windsurfing much more fun than paying bills or buying food
3 boards ranging from 2000 to 2009, 6 sails ranging from 2007 to 2009 bought new but in 2008 to 2010, 3 masts one boom.
I will replace when they wear out or I can get a big improvement by changing.
^^^ Pretty much the same - with the exception of a couple of old small sails that are handy on the odd occasion when it's nuking & a spare boom.
