I tasted passionfruit curd for the first time on a pavlova, I was lost to the intensity of the flavour. Where I live, passionfruit are extremely hard to find, and VERY expensive. I attempted the passionfruit curd recipe but used only half as many as suggested in the recipe (due to the cost) and thought the addition of a little meyer lemon juice might help. The curd, though beautiful, wasn't as flavoursome. However we do have a passionfruit juice, an import sold locally, by the "Rubicon" brand name. Could it be possible to use this in the recipe and add one, fresh, at the end with the seeds in? I am tempted also to try it to make a passionfruit jelly, just to see what happens. Do you think this could be possible?
Curds are usually made with acidic ingredients. One of the reasons for this is that the sharpness of the fruit cuts the richness of the butter. However the acid in the juice also reacts with the egg yolks in the recipe, thickening and stabilizing the mixture. Unfortunately the passionfruit juice that you mention is a "juice drink". If you look at the label then it is mainly water with some juice and some sugar added (you should be able to see the ingredients on the side of the packaging). So although it may be delicious as a juice drink, it is probably not going to work in the curd recipe as the favour will be very muted once the butter and eggs are added. The juice woud probably work in a jelly but you would need to use it as it is, without diluting it further.
It may be worth looking for pure passionfruit pulp (not the canned type in syrup) as this is sold in frozen form and also sometimes in chilled or UHT form in pouches. It is usually much more econmical than buying the individual passionfruit and although you may have to buy a larger quantity the frozen one lasts up to a year and if you buy a chilled or UHT pouch then the leftovers can be frozen and used another time. If there is a catering supplier near you then that would be a good place to start looking, or you may find it on-line. One passionfruit yields about 2 tablespoons/30ml puree (without seeds) so for Nigella's Passionfruit Curd recipe (from Domestic Goddess and on the Nigella website) you would need 300ml seedless puree plus one whole passionfruit.