Where can I buy a fretless guitar ?

Rondomusic sells some Agiles that are Fretless, besides that, most of the sold
fretless guitars are custom shop guitars, Vigier sells one or two different models
but these are pretty expensive (handbuilt in France).
Godin sells a fretless acoustic guitar, nylon stringed afaik.

But believe me, the idea sounds pretty cool, but it's really tough to play fretless
on a guitar, even more than on a bass.
You have to touch the strings exactly on the right point, especially for chords or
it will sound really, really out of tune, that part is pretty tough on a fretless bass
and due to the longer neck you don't have to be as spot on as on a guitar, it's still
tough.
If you come from a classical background, played violin or something like that it won't
be as hard probably, but after getting used to frets and playing a pretty chord based
instrument like guitar it may be really hard to adapt to the fretless concept.

These are the only two avaiable Agiles atm:
http://www.rondomusic.com/al3110hsbffretless.html
http://www.rondomusic.com/st625eb3tsfretless.html

If you got a cheap guitar around, you could actually defret it by yourself, did this to
a bass (and once on the bass of a friend) it's not that hard, but I wouldn't try it on
a expensive guitar.
You have to heat the frets (with a soldering iron for example - touch ONLY the frets
with it, just for 5-10 seconds) and than pull them out really slow with pincers.
After you've done that, sand the fretboard a little bit, put some wood glue into the
fretslots (you don't need much, just a tiny bit) and press some veneer in there.
Move on to the next fret, after you've done that, there's a lot of veneer you have to
cut off (from the top and the side of the fretboard), just use a sharp cutter and be
precise.
In the next step, sand the fretboard again so everyting feels consistent (don't sand
too much, just a bit with fine sandpaper) and oil the fretboard.
That's it actually, you've just defretted a guitar neck and got a fretless guitar.

WARNING: I would only do this to a guitar with a bolt on neck that wasn't expensive
and that you don't love!
Remove the strings, remove the neck, let the neck rest for 1-2 days, do the stuff I
wrote above, let the neck rest for 1-2 days, put it back on, put strings on it.
 
Wow thanks for all the info man ! That Agile is really not much expensive.
I thought about defretting a guitar but I don't think the fretboards on the fretless are just rosewood like on a guitar... But yeah, might be nice.

Well that wouldn't be to play chords really, more like arpegios. I already play scallop and like the feeling, and the feeling on a violin too.. so I think it would make good sense for me to have a fretless guitar even if it's hard to play ;P
I might hate it, who knows lol
 
it depends, many guitars (and basses) just use a normal fretboard for the fretless
versions, sometimes a bit thicker that it's not that bad if it wears a bit down.
Vigier uses some sort of metal (called iMetal, should help against feeling cold), but
most of them use ebony afaik because it is said to be a bit harder than rosewood,
but that depends on the tree...
Jaco Pastorious defretted his Fender Jazz Bass and put epoxy on the fretboard
to get it even, with that technique, it won't wear down as fast.
 
My brother defretted a bass and guitar. The bass turned out really well but the guitar is not nice at all.

You don't need to use veneer either. He used an epoxy (woodfiller) and filled the empty fret slot with it and sanded the whole fretboard to get rid of excess once it dried. It's easy to see the fret lines and it's perfectly flat with the fretboard. You score either side of the fret before pulling it out so that it doesn't crack the wood. It's easier on rosewood than on ebony or maple too as maple has a finish usually and ebony is a very brittle wood that can crack easily.

The bass is great- plays well and it has a decent sustain, sounds exactly like a fretless bass should. The guitar is very hard to play and there is very little sustain. He did it to a cheap harley benton that he got used and it'd be a shame to do it to a more expensive instrument.

You often see fretless guitars made with different neck/fretboard materials like metal to increase the sustain. I'm sure nylon strings work alot better than steel for it too.