The Infinity server's economic regulations can be learned about in-game as well as from this post.
Primitive Resource:
Items that can be gained en mass from the moment you join. Wood, dirt, cobblestone, sand are examples.
Essential Resource: ($1 - $4)
Stuff that is still pretty easy to get, but has a higher value. Ores, Ingots, several common mob drops.
Premium Resource: ($8 - $18)
The good stuff. Diamonds, Blaze Rods, higher level ingots.
Complex Item: ($30 - $100)
Anything that requires a few steps to make and can't just be pulled from the ground or a dead mob. Think machines.
End Game: ($150 - $300)
Top tier stuff. Awakened Draconium, Thaumcraft Ichor, Blood Magic Crystal Clusters.
Special Items:
Some items have a specific value they must be sold for. Creative Energy Cell, Everlasting Guilty Pool, Nether Stars.
Shops:
• Shops rented but unused for 24 hours will be unrented (you clicked rent but never did anything with it)
• Shops without any "shops" (chests with items able to be sold) will be unrented after 48 hours. Even if you build on it
• Shops that are 100% out of stock will be unrented after 7 days.
• Shops whose owners are 14 days offline will be unrented.
• Sold items must be clearly visible and readily displayed; no chest/sign combo without a Fancy Sign, DE placed item, or the like.
• You must sell at least 5 items in your shop. If you choose to have an off-site shop, you must instead sell at least 20 in your market shop; this does not include the items in your off-site shop.