To buy everything from Doma's shop, you'll need to find all 100 Priorite Shards dotted around Koboh, Coruscant, and the Shattered Moon.

You'll find plenty of Priorite Shards on your own along your journey, but the journey to collecting all 100 of them is tough without a guide. Luckily, there's a map upgrade you can get on Jedha which will show you the locations of each and every Priorite Shard (as well as Data Discs and Jedha Scrolls) if you know where to look.

You'll find the Treasures Map Upgrade in the Wayfinder's Tomb, a short distance from the Arid Flats meditation point. However, to unlock the map upgrade, you'll need to explore three locations:

Northern Desert Ruins (Path of Persistance) - Near Anchorite Base meditation point
Western Desert Ruins (Path of Conviction) - Near Desert Ridge meditation point
Southern Desert Ruins (Path of Restoration) - Near Desert Ridge meditation point

Each requires you to use your Force Push and Force Pull abilities to move balls along narrow passages, until they reach the top of the ruins, where you'll unlock a perk slot, and also go 1/3 of the way to unlocking the Wayfinder's Tomb.

Once you've done all three, return to the Wayfinder's Tomb and stand on the platform at the top, which will lift you down into the tomb itself. Here you'll find the Map Upgrade: Treasure, which will mark every Priorite Shard that you haven't discovered on your map.

You can press  on the map screen to see how many Priorite Shards you're missing from the area that you're in, making it easier to find them all, and you can also press  on the map screen to go into the Legend and hide every symbol other than Relics, which will show you Priorite Shards, Datadiscs, and Jedha Scrolls. Use this to hunt down every last Priorite Shard that you're missing, and then return to Doma's shop to spend them all and unlock the achievement.