... book about economy is your best bet.
Not to poke fun at you, but you would want a book on Economics. More specifically, you would probably want an introductory book on Macroeconomics.
Anyways, my question is, is there a "best" way or a "right" way to set up a mud economy? or are most economy systems basically the same?
In short, no, there is no right way. As an undergraduate majoring in both computer science and economics, I can tell you I have spent a lot of time researching this issue.
Overall, grabbing an introductory economics book would help you immensely. However, if instead you want something a bit closer to MUD design in general, I would highly suggest Designing Virtual Worlds by Richard Bartle. He has a fantastic analysis of MMO economies and their function; plus, the entire book is a must have for any serous MUD developer (and the information is extremely beneficial when applied to other games). I'll go over some of his and my thoughts briefly.
Perhaps the biggest thing you should consider is if you need to implement an economy at all. Game economies of a persistent world are perhaps the hardest thing to calibrate and get right. There are numerous examples of badly managed and designed economies (such as Lineage II, where it takes billions to buy anything worthwhile, so you end up with alts just to hold your cash), so you can avoid a lot of hassle if you can eliminate it entirely. If this is not befitting of your game then you will have to carefully watch it to make sure it stays reasonable.
The biggest factor on how your economy will function is how you let your players interact with it. Can they sell items to NPCs? What about other players? If you allow player to player selling then you just opened a huge box of intricacies which I will try to briefly address.
To some extent, you should expect normal free market behaviors. That is, as supply goes up then prices will drop until demand is met. If demand is high then prices can and do skyrocket. Expect and plan for inflation; as you inject more money into the game money will gradually become less and less valuable.
Some of these things can be mitigated, and often significantly so. One tactic employed by many MMOs (FFXI, WoW) is to have NPCs drop items, not money (or not much money). This gives you a lot of control over money being injected directly; players will have to sell items, some vendors might pay more or less (or not buy an item at all). The amounts for items sold to NPCs is usually very low, making it a last resort for players. That is, it is better for them to try and sell items to other players as long as what they can get from that sale exceeds what the vendor is willing to pay. This also gives you a way to inject crafting mats and other things into the game if you so desire. In general, this avoids people farming certain mobs that tend to drop high amounts of gold.
Have common and frequently used items available from NPCs. This sets a market cap, as each smart player should always seek out the lowest prices on goods of equal quality. This avoids someone taking something that is needed for lots of things and selling it for obscene amounts of money, which causes farming and currency/market skewing and can also cause annoyance to players. For example, in WoW you can buy the mats needed to cast some spells from vendors, so no one bothers to enter this market and thusly each character can -always- buy what they need to literally play the game. (imagine if you couldn't find someone with the mats available and you could no longer resurrect people!) However, Wool Cloth can be fairly hard to come by and is needed for various things (rep rewards, xp, leveling first aid, etc), but this item is not available from vendors. A low level character can often net large sums of gold for the Wool he has collected, transferring large amounts of wealth from max level characters to lower level characters (which creates skewing).
Overall, this culminates with the idea that, if your economy is sufficiently complex, you need to force your players to spend money. In a sense, the game becomes very similar to the Fed -- it needs to regulate the money supply in order to maintain economic order and keep inflation in check.
In terms of economics, inflation is the biggest risk of destroying your game. The more people that play, the more wealth the game literally injects into the economy. Thus, a game with 1000 players will have an economy drastically different then the same game was with 50.