Composting Productive Plants

I usually grow about 8 or 9 gherkin plants and that gives us enough for a year's supply of cornichons plus a few jars to give away/inflict on the innocent. This year I have 10 plants (over two sowings), but the first three are really productive and have already produced a year's supply of pickles.

It seems wrong to compost the rest of the plants before they've even produced a gherkin, but I don't want to spend any more money on vinegar for pickling, either. 

Should I keep on pickling and reckon to not grow any next year (and possibly the year after!) or just be hard-hearted, compost the lot and use the space for something else?!