What do you suppose is your most valuable item?  

Probably our 7' rosewood buff...
Probably our 7' rosewood buffet with tambour doors, Danish, which goes with the 7' two-leaf Danish rosewood table and the six rosewood Møller chairs, all of which I'd trade down for a teak set if and when I find the right one. I like rosewood but I'd be just as happy with good old teak.
That's value as in monetary. I have other stuff that isn't worth nearly as much money but that I value way more.

A sense of discretion.
A sense of discretion.

My Hans J. Wegner's Sawbuck...
My Hans J. Wegner's Sawbuck lounge chair. It's the very rare unupholstered version in teak and beech (not oak), but what makes my example special is that the armrests are in mahoghani. There's also a "1" carved under the seat, so it might be pre-production or a prototype. My father bought the chair for his parents along with one more Sawbuck lounge chair, though upholstered in striped Greenlandish wool (disappeared many years ago). My chair is in 95% mint condition with a beautiful patina since it spend all its life just sitting in the corner of their guest room.
I also have a bench/table from Bovirke by Finn Juhl in palisander and brass edges (the longest version). My father had it in his office since new and used it to lay his paperwork on, so it too is in an amazing condition for its age.
I like this thread, always interesting to see what gems are hiding in people's homes or collections. It's the rarity aspect I like.

value measurement
The value of any commodity is based on the amount an individual is willing to pay to pocess that item. An average of 25 cents on the dollar for "high end", brand manufacturing, designer furniture and objects new or floor samples (no shop wear)is my maximum number for acquisition. This is an average. Greater disposable income combined with frequent purchases (repeat vendors until all the desired inventoery is exhasted) will always yield the lowest retail cost. Hence the value of my collection is probably the lowest and does not warrant detailing.

I cares
So I know whose house to rob.

?
This reminds me of a customer I had who always asked how exspensive something was before deciding if she liked it.

I`m with you on this one Tynellbuyer, I like your style.

My most valuable Item(s)...
My most valuable Item(s) where flogged years ago
Now I'm just left with my favourites
;O)

A better
thread would be "which piece has the best story?". Lucifersum's stories of the Magic Dumpster are always hilarious, for example. Spanky's always got great before-and-after stories because she is so talented.
Here's one. This piece of folk art that we will call "Bertrand" for obvious reasons, was found laying on the ground on a blanket at a flea market in Belgium. I just loved him, I don't know why. Mr. Big hated him. Absolutely hated him. "Why are you buying that hideous thing?" "Because I like him and he only cost 10 euros!" Duh!
I made him tote this statue in his bookbag,(because Bertrand was too big for my bookbag AND Bertrand made each of our suitcases too overweight for the plane), all over Belgium, France and Switzerland. Now, Mr. Big won't even look at poor Bertrand. I have to hide him in a corner of my office.
Everytime I look at Bertrand, I smile.

How much...
Will you sell Bertrand for?

Smiles
don't come cheap, buddy. Bertrand is priceless.

Jesgord and Betrand
both made me smile.
"Valuable" is totally the wrong word choice here. It is far too loaded and variable to have an a decent discussion. Perhaps it is the approaching holiday season (or perhaps the collapsed economy) but I find monetary focus to be a little vulgar.
Value varies depending on usage, purpose, and intent. Something valuable to a dealer might have no value at all to a layperson. A lower-income person in Goodwill might find much more value in a comfortable, secondhand couch than in a ceramic ashtray.
Or perhaps a better example would be the same item, lets say a Papa Bear chair. One person finds it and has no idea what it is (other than a comfortable chair and uses it for a lifetime. A dealer finds the same chair - and sells it for $20,000. Who has gained the most value from the chair?

Lucifersum, you are such a delight,
too bad I moved away from MA before getting a chance to met you 'live'. You are so, so right. It's a thing; things have monetary value, but true value comes from the experience of living life. I pity the person who reckons value only in terms of money.
Bertrand is quite funny! I'd hide him in the loo to spook my guests!

I possess numerous pieces...
I possess numerous pieces appraised at sums in the seven figure range--some, let's just say, considerably higher.
But what I regard as my most valuable piece is a small, shapeless, drably colored hunk of crochet, the unfinished final work of an exceptionally beautiful and fatally ill young girl.