Purchasing weapons with special ability

[Lavios Daleborn]

When you purchase a weapon with a special ability, do you pick the weapon you want and then roll to see what ability you get or do you pick the ability?

[Kazaan]

It depends on the size of the settlement in which you shop. For smaller towns and villages, they may have a very limited selection of magical weapons available a la carte so you'd roll to see what's readily available and, if it isn't available, you'd have to make a custom order (which would take crafting time). For larger cities, there may be a presumption that "anything lower than such-and-such gold is considered readily available" and only higher-value items would need to be rolled for.

[Bronnwynn]

Well. Strictly speaking, it depends on the GM - I, and all the people I play with, either assume "No magic items for sale (or possibly even crafting)" or "Small list of random magic items, selected before you even look through the markets, all mundane items under the price cap, and if you want, you can get anything commissioned by caster level" where "by caster level" means that the maximum level of spellcasting you can get is the maximum caster level, so you can only commission things that people with a CL = or < that in a given town.

Of course, commissioning costs full price and takes a lot of time for expensive stuff.

Also, it's never say "I want this item." "Okay. It has these magic powers."

[Lavios Daleborn]

Okay, thanks.

[Lifat]

Your original post sounds a bit like buying a weapon and then have a random chance to get each different property.
That would be a very unique way of running things and definitely outside normal. I would personally hate such a system.
The way I usually see it run is like this:
Each settlement has the following characteristica:

A lower gp limit where any item under this limit is readily available (if set to zero then all items must be rolled for)

Then items above the lower limit is rolled for. Usually there is a set amount of magic items and a max price on each item.

A restock time, which is the time it takes for a settlement to sell the currently available items and make/order new ones. If the party buys some of the currently available items then they shorten the restock time.

All settlements also has a maximum CL on magic items that they can make. The party CAN order items with a higher CL if they are willing to wait for the settlement to get the item.

If the party either don't want any of the current available items and don't want to wait for the items to get restocked and don't want to wait for their order to get in from other settlements, then they will have to go to a new settlement in the hopes of better/different items.