id reccomend looking on trademe at the killies for sale, or even visiting killie keepers and having a look at the species available and pick which specie you like.
No matter what killie you get if you have any problems just ask away on here, there are many people to help out.
they are very easy to breed aswell, im having more luck with my killies breeding than i am with my guppies. They just require a little bit of effort and equipment.
When i started my killies only lived on flake and i had low breeding success, they now get flake, micro worms, white worms and brine shrimp and now i only pick the mops weekly because i get so many eggs, i think the record is about 30 eggs from one pair.