There are various ways to get the last blood pieces if you are in a guild that hunts in demiplane. Most guilds doing that have guildmembers that will make the cultural gear for you if you provide the most expensive parts, e.g. metallic drake scales. Those can be looted for free in Nest zones. Depends on what piece you want as to how many of them you need. And each symbol that goes in the cultural gear also requires an MDS.
On our server, typically if you ask an out of guild smith to make you the gear, its the metallic drake scales needed + 10K for the combine. Or as a previous poster said, people have them for sale in the bazaar. Usually its cheaper if you provide the scales to a smith instead.
A guild that hunts in demiplane will often collect many of the drops needed during raids. Ours does and our banker who also makes the AAAAs, posts a list of things that guildmembers will need to contribute to the bank in order to be given an AAAAA and the rest of the pieces to create a last blood aug.
Our members get the stuff on the list and put it in the bank. At the end I think there is a certain amount of pp required for the ore etc to make the AAAA, under 13K iirc. So when you have all the parts on the list, and 13K to hand in, the banker will make you an AAAA the seal and the goo. 13K plus a little farming beats the hell out of the bazaar AAAAs which typically go for 100K+.
Then you loot a last blood in Demiplane and combine and put it in your gear.
If your guild hunts in Demiplane, you might contact the banker first and find out if any guildmembers are smiths, tinkerers, researchers etc and can make the gear and AAAA for you.
Any race can make your symbols either with tailoring or smithing. You'll have to use someone of the same race as yourself to make your cultural gear.
Not talking down to you, just putting out the info as I know it. Take what you want out of the post, ignore what you already know
If you are not in a demiplane raiding guild, I think you probably are SOL for Last Bloods. They are no drop, off boss mobs, and in an instanced raid. And you must be able to loot in Demiplane i.e. have a drop of Accursed Blood from a tier 2 boss... or have completed 5/5 of the DoD trials (sendai, bloodeye, council of nine, emperor draygun and shyra) in order to be able to loot there. You can get gimped in if you have the Vule piece and the tasks done, but you wont be able to loot until 5/5 or have the drop of accursed blood. So its not really likely if you dont belong to a demiplane guild, that you would ever be able to actually loot one.