The Thaumaturgical Fair in Venice

If there doesn't happen to be a Tribunal that year, Midsummer in Venice hosts a most interesting fair, where magi gather to do trading. (Venice appears to be "neutral ground" amongst magi of the Roman Tribunal.)

Magi are, of course, far too dignified to set up booths like common merchants; few have so many wares as to make such a display worthwhile. Instead, the fair takes the form of a large banquet in a hall with many small alcoves off to the side; Magvillus, Domus Magnus of House Guernicus, owns the space, and considers it useful that it seem occupied more often than every seventh year, when it hosts the Roman Tribunal. Magi spend their time in professional discourse; those with more straightforward goals will even write what they are buying or selling in chalk upon a large slab of slate, to facilitate multi-way exchanges.

Vis is, of course, one of the greatest means of exchange. The Roman Tribunal is the best place to sell vis in all of civilization, and trading goes furiously. (This factor, combined with Italy's central location within the Order, weighs heavily in the choice of Venice for this fair.)

About half of Verdi turns up to these gatherings, seeking to sell their creations or commissions for more. There are usually a number of Tytali present, though they seldom have straightforward motives.

Some notes on vis trading:

Vim is in an interesting position, as it is the easiest to come by (though distillation) but the most useful of all the Forms. Distilled Vim vis is the most reliable medium of exchange in the Order, and there is a de facto standard of these being worth 300 silver per pawn in the Roman Tribunal.
Technique vis tends to be worth twice as much as Form vis, though quality varies with price. Flambeaux commonly will bid for Perdo and Creo vis. Intéllego is perhaps the rarest of all.
Animál vis is very cheap, and Herbam vis literally grows on trees. These will run from 200 to 250 silver per pawn, depending on demand.
Corpus vis is almost as popular as Vim, due to the need for longevity potions within the Order; highly reliable Corpus vis (such as Amurgsval beer) has no difficulty fetching 300 silver per pawn.
Elemental vis can be tricky to find, and Ignem goes for good prices due to the competition from Flambeaux spending Moorish treasure on the stuff. The other three elements can be a bit cheaper, but not are not always present for trading.
Mentem and Imaginem tend to be similar in price and availability: more common than the elements, less so than Animál and Herbam. They are not as valuable as Vim and Corpus.

Magi trade other things as well. Spells and lab texts are popular, and it is possible to pick up complete laboratories (assembled by apprentices) for cash. One can often find complete grimoires for sale by someone who has decided to compile a group of useful spells together. Verditii, newly arrived from Verdi for the occasion, often know just what you're looking for in the archives of Verdi, though the general consensus on their apparent ignorance of the most advanced enchantments is that it is merely a reflection of their desire for repeat business.

Some Flambeaux, in need of cash or vis, will turn up selling their services as slayers of great beasts, hoping to profit by ending the troubles of young covenants. Many mundane texts trade hands here, and upon occasion, a magus will bring a tome on a particular Art and auction it to the highest bidder.