First time topic, Fresh 80
you can get them from other sources but these are the best place to get them from
Amulet=Laurel Vendor
Accessories=Guild Commendation Vendor
Rings=Fractals with pristine relics
Back item=Bloodstone Fen
When picking gear ascended gear is unique which means you can only have one of each equipped. They can have the same stats just have to be diffent names.
If you like grinding there is Bloodstone Fen were you can get ascended ring, amulet and back item.
Remember that amulets can no longer accept AR infusions, so you can leave those off your shopping list for time being.
You can get cheap trinkets by doing the HoT story achievements. They are fairly straight forward, except for the final chapter (i.e the Migraine achievement).
If you’re looking for ascended sinister trinkets to match your armor, those can only be obtained if you have LS2.
Imo for ascended sinister or (even better) viper, bloodstone fen is the way to go for backpiece/rings/amulet. Aiming to complete the bsf map dailies (and maybe mine some bloodstone nodes or do some boss) should not take too much of your time and should give you an ascended every week or less, depending on the time you invest.
For accessories the options are limited atm.All kind of accessories are available through raids (viper and sinister included). Besides that, sinister is only available via doing the LS2 achievements which takes a lot of time to get and probably money too if you don’t have ls2 unlocked. The alternative is aiming for suboptimal stats like rampager/rabid from commendation vendor.
There is also the hope of asc accessories with the new stats being added with the new map in 2 weeks or so, which is not entirely impossible
as a sidenote, the lvl78 exotic backpacks from crafting disciplines come with 1 infusion slot, that could help you with managing your AR till you get an ascended infused backpiece