Although this should be very simple to do,you need to know some rules and what look for or it can be costly.
1. While Frangipani Seeds are allowed into Australia there are a few rules you have to follow. All frangipani seeds have to be identified so you need to ensure the seller writes the Genus(Plumeria) and the Species(Obtusa, Rubra, Stenophylla, etc) on every seed packet(along with the common name) and on the outside of the envelope as well, failure to do this will lead to AQIS(quarantine) seizing the seeds and destroying them. Some sellers actually include a Phyto(sanitary) certificate with their seeds which declares them as disease free, these are reliable sellers.
2. Watch out for pictures that have been adjusted with a software program. Although most sellers are honest there are some that are not, they will adjust the flower picture by enhancing the colour to entice unsuspecting buyers to get their seeds. Look for pictures where the flowers have just been placed over the leaves, this can be very obvious, also look at the leaves etc in the background, if they are darker or different to normal leaves then the colours probably have been adjusted. There are some amazing colours now available in frangipani but if the flower colours look too good to be true they usually are so check around and ask an expert in frangipani about them. This can happen in Australia as well as overseas so always be careful although some local sellers are only on selling what they have bought from overseas so they are totally depending on their sellers honesty about the colours.
3. Always read the feedback for the seller and look to see if they have a lot of repeat business, this is always a good guide to their quality of seeds, there are several top seed buyers on ebay that will always buy from the reliable sellers & they can act as a good guide also, you can even ask these buyers to recommend sellers to you.
4. Remember that seeds will never be exactly the same as their parent tree, there are more genes in a frangipani than a human so every seed in a pod can be a different colour. Be very wary of a seller that does not warn you that seeds will not be a replica of their parent, they may look similar but that is as close as they can be, they can never be exactly the same. You can end up with whites from any seed pod so do not believe that you will have a replica of the parent as it just does not happen, the best you can hope for is that it has some of the features of the parent, i.e. colour and petal shape, size, leaf shape/colour etc.
5. When the seeds arrive check them very carefully to make sure that they are viable, you should be able to feel the cotyledons inside the husk and they should be slightly fat and firm. If they are flat or they feel crumbly between your fingers they are no good. If you have any doubts peel a thin strip from one side and look to see if the seed is white, do not worry about this as it will help the seed to germinate bit quicker. If the seeds are suspect let the seller know so they can replace them or refund your money.
If you follow these guides you should end up with good viable seeds.