Getting around Jakarta is a problem. The city layout is chaotic and totally bewildering, traffic is indisputably the worst in South-East Asia with horrendous traffic jams slowing the city to a crawl during rush hour, and the current railway system is inadequate to say the least. The construction of a monorail system, started in 2004, soon ground to a halt over political infighting and the main glimmer of hope is the gradually expanding busway system.
The Jakartan equivalent to Thailand's tuk-tuk is the bajaj, orange mutant scooters souped up in India into tricycles that carry passengers in a small cabin at the back.
There are no set prices, but a short hop of a few city blocks shouldn't cost much more than Rp 5000. Be sure to agree to (read: haggle) a price before you set off! Bajaj drivers are happy to overcharge visitors. Locals who regularly use the bajaj know what a typical fare should be and are happy to tell you.
Also, since bajaj aren't allowed on some of the larger roads in Jakarta, your route may well take you through the bewildering warren of backstreets. Try to keep an eye on what direction you're going, because some unscrupulous bajaj drivers see nothing wrong with taking the "scenic" route and then charging you double or triple the price.