Blackmarket is continuously growing to encompass RuneScape's realm, Gielinor. As in every popular online game, there is an ineradicable tendency that virtual goods are sold for real money or traded for another virtual goods gaining unfair benefits during the gameplay.
Looking back few years in RuneScape's history there was a peaceful quiet period, in which Real World Trading (RWT) was not possible for most of the players. For two years RWT is back, the game has completely changed (ruined in my eyes), which is reflected in the black market gold prices as well. (Gold prices have dropped from $0.85/M to $0.25/M)
There are two kinds of digital goods to be sold regarding RuneScape: gold (gold pieces, gp), and accounts (acc, accs).
Selling accounts is very risky and non-rewarding. There are three well-known RS auction sites: gold4fun.com (formerly gold4rs), playerauctions.com, scythe.org. I prefer gold4fun out of these, but it has a huge drawback - the prices.
1 level 99 skill worths $5 if other skills are level 1 respectively
more maxed levels worth $5 each if other levels are not trained at all
0-1500 total levels: $0-19
1500-2000 total levels: $20-$29
2000-2100 total levels: $30-$39
2100-2200 total levels: $40-$49
2200-2300 total levels: $50-$79
2300-2496 total levels: $80-$140
These guide prices are based on my previous experience at gold4fun. Remember, none of these are good prices, but if you go for a secure trade, do it!
Having to choose which was more rewarding I'd say gold farming. Gold farming is the process of producing virtual gold for later sale. The most common way of doing this is botting. If you wish to choose the 'fair play', your choice will be merchanting - milking the Grand Exchange, RuneScape's stock market.
If you have never botted before, visit powerbot.org. You will be surprised how many of the fellow RuneScape players are actually using preprogrammed scripts for doing everyday jobs such as mining, runecrafting or prayer training. There are crazy bots as well optimized for player killing, collecting stuff, and even merchanting. Most of the best ones -unfortunately- are premium scripts, so you have to pay to use them. If you have Java programming experiences, powerbot's admin has made a great API for RuneScape bot development. You can do your own scripts using your blockbuster ideas. You can also sell your scripts as 'premium' for a really good income. By the way if a script gets overused, the produced items' price drops, so using the script will be useless.
The technical part of botting
Register on powerbot.org and confirm it via the link in your mail. You must get an application written in Java (more than 100 thousand players use it, so it's safe, you can trust me). The app itself can be downloaded by the big 'download' button taking up all space on the screen on the index page. The newest version may be buggy and may not launch, so check the website regurarely for fixes. It's very important since Jagex pays huge attention to blocking automated systems. The app needn't to be installed since it's a Java package. All you need to do is to launch it and log in. After logging in you can add a new tab. On each tab you can run a bot on a separate RS account. More tabs require VIP membership sold for $6.99 a month. If you think you can easily farm enough money to cover that, consider buying it. Running more bots at once takes up lots of computer resources. It's recommended that as a VIP run bots on the lowest graphics possible (this applies to your OS as well, use classic Windows!!) for lower memory usage. One tab takes up to 500Mb. With 2Gb RAM it's possible to run 3 or 4 at once. It's important to bot on more accounts at the same time - in other cases it's a waste of time, isn't it?
The classic merchanting involving street trade is no longer popular. The new art of it is manipulating Grand Exchange prices guessing the change of supply and demand. There are various techniques such as instant and overnight flipping, investing, and so on, there is a great blog about them.
Golds can be sold very fast either on the powerbot forum board or on gold4rs website. Latter pays less. There's only one option for payment in both cases: PayPal. Don't trade anyone from powerbot with less than 50 reputation - especially don't go first. Remember that PayPal transactions can be reversed, so you may become victim of an internet fraud.
Written by Andras Rapli, 2013