Honestly, the "reasonable" item pricing is as much reasonable as you want it to be, regardless of the item's starting value. It really doesn't matter if a short sword costs 10 copper, 1gp or 100gp. You do however need to understand how easily the player can earn 10 copper, 1gp and 100gp. To keep the items' pricing concise you should create a few tables with pricing modifying factors to make your life easier and to make sure that a superior steel knife will never cost more than a superior steel battleaxe, rarity aside of course.
First, decide a base value for each item class (in case of doubt just use the items' overall weight and translate it into coin).
- Knife - 18gp
- Short Sword - 29gp
- Great Sword - 40gp
- Axe 30gp
- Battleaxe 48gp
- Mace 27gp
- Helmet 33gp
- Plate Armor 144gp
- Boots 12gp
Now create a materials table with its corresponding price multiplier (materials should dictate the item's durability as well as the items' score output for protection and damage:
- Common Wood *0.2
- Ebony Wood *0.4
- Copper *0.8
- Iron *1
- Steel *1.4
- Ebony Metal *2.0
- Dragon Bone *2.5
Now you can add another table for quality (quality should dictate the items' score for protection or damage):
- Broken *0.2
- Decayed *0.4
- Crude *0.7
- Common *1
- Balanced *1.5
- Superior *2.5
- Masterwork *3.0
To conclude this example we add the rarity table:
- Common *1
- Uncommon *1.5
- Semi-rare *2.2
- Rare *3.0
- Unique *4.5
So now lets see the output of some items produced using these tables:Decayed Iron Short Sword (Common) = 29gp * 0.4 * 1 * 1 =
11gpSuperior Steel Battleaxe (Rare) = 48gp * 1.4 * 2.5 * 3 =
504gp Crude Copper Helmet (Common) = 33gp * 0.8 * 0.7 * 1 =
18gpBalanced Ebony Plate Armor (Unique) = 144gp * 1.5 * 2 * 4.5 =
1944gpThese modifiers need of course to be balanced with world setting itself. As I stated at the very beginning of this post, you should take into severe consideration how easily it will be for the player to harvest money. Restricting items appearance to the player's current level could also be a solution as well as changing the item's price range depending on the player's geographic position. Some cities could have scarce access to metals making everything they sell made out of metal costing substantially more. Please, understand that this was just an example, some multiplying factors do not make that much sense at all so free to revise them
I hope it helped in any possible way.