All Ascended tier gear is Account-bound now, so you can purchase it freely from wherever you like without worrying about that. The best places to get Ascended trinkets are as follows:
Rings: Fractals. The laurel cost requires a minimum of 25 dailies plus monthly, meaning you can only get them from Laurels at a rate of one per month. Your Fractal acquisition rate will be much higher; at a Fractal level of 10, you can complete a run once daily with relative ease for one guaranteed Pristine Fractal Relic (10 of which get you a ring) and a decent chance at a ring dropping (stats will be random though). This means the fastest possible acquisition of a ring would be daily, with longest possible acquisition being every 10 days. If you aren't too bad or bored at Fractals and level up to higher reward levels, every 10 gets you a new daily tier that can be completed for an additional relic and additional chance at a ring. I did two Fractals today, one in at 17 (for the 10-20 tier) and one at 26 (for the 20-30 tier), and received two Rings and two Pristine Relics. Leveling up to the respective reward tiers is a little time-intensive, but not horrible, and unlocks for your entire account, making it a once-only effort. In addition, fractals have great drop rates on rares, lodestones, and other useful items, as well as rewarding tokens which can be exchanged for boxes, obsidian shards, and other useful loot. Fractals also have a decent chance at dropping Vials of Mists Essence, which is used in some Ascended backpack crafting recipes.
Necklace: Laurels. Bonus tip: Purchase them from a Laurel Vendor in WvW, as they come at a discounted laurel price, in exchange for Badges of Honor (which you can swim in just from zerging in EotM for a little while). Maximum acquisition rate: One every 10 days, plus monthly achievement reward, or one every 20 days if monthly achievement reward has already been used.
Accessory/Earring thing: Guild commendation vendor. Your account can earn a maximum of 6 guild commendations each week by completing Guild Missions. 12 Guild Commendations and 5 gold will get you an accessory. Maximum rate of acquisition: One every two weeks.
Backpiece: This is a personal choice. For cost, the most efficient way is the Spinal Blades backpiece, afaik. Stats will be selectable. Rate of acquisition will vary. For "want it now", go with a book/quiver. It'll cost you in the form of 50 ecto and stack of the stat-related t6 mat, and will also require a Vial of Mists Essence. Rate of acquisition will vary.
Armor: Crafted only (or very rare drop, but unreliable method). Rate of acquisition will vary. Cost varies based on weight and stat selection, expect 50-100g per piece on average. Requires 500 in an armor crafting discipline.
Weapon: Crafted only (or very rare drop, but unreliable method). Rate of acquisition will vary. Cost varies based on weight and stat selection, expect 30-70g per weapon on average. Requires 500 in a weapon crafting discipline.