Periwinkle plant for ground cover

Hi - does anyone know where I can source some of these plants please. If they are a weed an alternative recommendation would be OK. They are for a shady patch under a kowhai (mine) and overgrown feijoa(neighbours).
TIA

Be very careful if you plant these, as they can spread, your neighbours will not thank you if they get into next door, not quite sure how they are propagated, best to check with your council to see if they are a noxious weed
Plenty of plants here if you want to pay post and packing , maybe try local first.

OK bill - how about some ideas then?

nonumbers, bill is quite correct in warning you that these trailing plants can become a problem if left to go unchecked - but then again - so can so many things! The one that causes most problems is Vinca major (the larger leaved and flowered variety you so often see in wasteland) There is a smaller variety, of which there are several cultivars (highly prized by some) and, although they, too, can become a bit naughty, are much more easily controlled. There is a white one, Gertrude Jekyll, a double plum coloured one, a variegated (lime and dark green) leaf called Golden Wanderer which has the traditional pale blue/lilac coloured flower. This smaller leaved and flowered variety is called Vinca Minor. They all distribute themselves more widely by putting down roots at the leaf axils along the stems. Where the stem touches the ground, you'll find them, so their long growths can have many sets of roots to keep it fed and expanding! But all that is needed is a stern cut back to keep in check. They will, however, form a very dense mat which pretty much precludes anything else getting a look in.
There are always other options though. Ajuga, Symphytum grandiflorum, violets, Pulmonaria, Pachysandra terminalis, even something like Phlox stolonifera - but of course some of these would be seasonally attractive - not necessarily all year. There would be many more options but only you know your conditions and how much effort you want to expend on keeping the patch looking good. I suggest you spend a bit of time at your local library (much more reliable than Google, generally!) and then you can really make an informed decision as to what might suit you best.

I've got a variegated one as a ground cover here - must have had it more than 10 years and it isn't a problem yet.

Thanks piquant - the bed I had in mind is well containable from wandering suckers and just needs that solid mat you mentioned to keep weeds etc at bay. So where do I buy it?

Well, if you have a nice little perennial nursery somewhere in your area, you could try that. You may find it in a garden centre but these days a lot of them don't seem to have a lot of variety. Failing that - try the online nurseries - maybe Mauways, - if you googled it in NZ it may come up with some answers for you. if all else fails - let me know. Any particular one attract you?