Follow artisan equipment
A collection tier is a source of options, not a universal power score.
Start with the maker
An artisan can offer several collections. Their tiered item lists and masterpiece are distinct: an item’s presence in a collection does not mean it is guaranteed on the next delivery. Keep the actual collection and tier with the item you are pursuing.
Compare the object, not its price
For weapons, compare damage dice, critical range, reach and enchantments. For armor, the armor bonus is only part of the choice: the Dexterity cap, check penalty and spell-failure chance can matter more to the intended character. Price is not a substitute for these properties.
Artifact shards
A shard such as the Dwarven Helm Shard or the Melted Shard of a Ring is part of a destroyed artifact. The game's own description says that once you find all of the fragments, an artisan with enough skill can restore the artifact. Your inventory lists the shards you carry, so it already shows which ones you have. Several items share the name First Crown Fragment and are still separate objects.
Leave with a concrete goal
Pick equipment that fits the character and note which artisan or fragment it depends on. A stronger individual item is useful only when the intended character can actually use it.