I don't really know much about Pathfinder, but if I had to make up some prices, I'd assume that, if the players want to buy it, it's because they have a use for it. Thus, I'd start from the same price as for the corresponding uncursed item, on the assumption that they'll be about as useful in the hands of a clever player, and then maybe reduce that a bit (say, 10% to 30%) if there seems to be no obvious way to turn the curse into an advantage.
Note that the above is for players deliberately seeking to buy a cursed item. It might be possible to find disreputable merchants trying to pass off a cursed item as the real thing, possibly at a considerable discount, but such merchants would be unlikely to advertise the item as cursed or openly reveal its nature (since they wouldn't expect most buyers to actually want a cursed item).
Similarly, since there presumably isn't much market for such items (except perhaps in very disreputable circles), I wouldn't expect most merchants to want to buy them. Indeed, there might even be laws, or at least strong societal norms, against selling cursed items. (Just try to deliberately buy some unsafe machinery or hazardous waste IRL, and see if anyone will sell you any.) Thus, players looking to sell an item known to be cursed should only be able to do it at a very significant discount, if at all, at least unless they just happen to know the right kind of people (or unless they can pass it off as uncursed).
Indeed, depending on how involved you want to make this, finding the kind of people who engage in trading cursed items (and/or convincing them that you're genuinely interested in buying them) might constitute an interesting subplot in and of itself, and could be used to generate future plot hooks by giving the players some connections to the not-quite-so-public side of the local economy. Or, if you'd rather not to go there, you can just abstract it away and say "yes, you can buy it, but it'll cost almost as much as the uncursed kind."
Edit: I did find something in the Pathfinder rules that sort of talks about the price of cursed items, namely a remark that "Cursed items can be sold, if the curse is not known to the buyer, as if they were the item they appear to be."
This at least implies that, if the players are unscrupulous enough, they might be able to sell their cursed items at full price simply by not revealing that they're cursed (and getting away before the buyer notices). Of course, if the buyer decides to identify the item and beats the DC by 10 or more, the players might have some explaining to do.
This also suggests that an equally unscrupulous trader might be willing to pay a reasonable fraction of the full price even for an items they know to be cursed, on the assumption that they'll be able to trick someone else into buying it for the full price.
It also suggests that any merchants (more or less) openly selling cursed items should not be willing to sell them for too much less than the full price, since they could presumably always either try to pass them off as uncursed themselves, or at least find a buyer willing to do so. The exact discount, as compared to the price of an uncursed item, should depend on the risk and consequences of being caught doing that, and would seem likely to vary between vendors.