Unlike many other games, wealth is perceived differently. 20G may not seem like much, but in the game perspective, this is actually a decent amount of wealth, and it can get you some good items. The same can also be said about the market value of various items including weapons, clothing, and synthesis materials. The key to understanding this unique economy is accepting "low value." Before further explaining this idea, it's important to note that the minimum and maximum range of wealth that players can carry: 0.02G to 9999.99G. With that being said, let's continue.
Actions That Affect Economy
Seeking Short-term Profits
No, no, and no. This is the kind of attitude that leads to economic disasters (in the real world). Even in a game that seems to provided limitless materials, selling prices for much less than their market value will cause other players to try and lower their prices to gain profit. Consequently, this will drive the market value for that item, causing problems in the supply and demand for that item. Although this may seem good for buyers in some aspects, sellers would have to sell less items so that they don't risk losing substantial marginal profit. As a result, there's less incentive to gather that specific item, and eventually the item loses market stability for some time.
Although Puppet Guardian isn't designed to have a trade system, there is a way to trade with other players. Generally, players will each other items for very low prices. However, there are a few problems with trading. One common issue is item scamming. Because players are forced to post low prices to attempt a trade, they are also taking a risk in which the other person may end up "stealing" the item rather than keeping to the trade agreement. Many players sometimes wonder why game developers haven't designed a trade system for Puppet Guardian. To answer this question, because players choose to trade items rather than post them up in the Merchant Guild, there are many cases in which the value of different items will vary inconsistently thus creating an unstable economy. The main purpose for the Merchant Guild (or the market system in this matter) is to create player-incentive to establish stable market values for many of the items in Puppet Guardian. In a way, it's a reflection on how economies work in this day and age. Many of the transactions perform in the real world almost always involves some currency.
Using the Merchant Guild as Storage
The purpose of the Merchant Guild is to sell items, not take advantage of the space being provided. This action can potentially influence (or confuse) other beginner-level players to post prices that seem unreasonable. At the very least, post your items for 9999.99G so other players know that these items are not for sale. The merchant NPC has enough to keep track of as is, so let's be respectful to the guy and give him some space.