OOC: Okay, my assumptions are as follows: (1) the party will spend a small portion of the money available on torches and tindertwigs, and (2) the party will descend into the lowest reaches of the towers to look for a guide that can help them find a suitable entrance into the sewers. The party can buy as many torches and tindertwigs (or even lanterns, oil, or sunrods) as they can carry at the rates listed in the PHB. Just tell me how much money you want to spend. As for number 2...
Everyone: Lady Elaydren's map leads you through a tangle of streets and stairs deep into the bowels of Dorasharn Tower. Little light from above enters into the tunnels and corridors in these levels, and their cobblestone streets and passageways are damp with runoff from the previous night's rainstorms. Occasional windows give views of other towers, other corridors, other places, while rotten wooden torches splutter and gasp. A thick smoke hangs over your heads.
The poor and downtrodden crowd around at corners. Urchins in ragged clothes peer at you from sooty pools of light. Shady looking men and women leer at you, with more than one offering their "services" for "not more than a silver." The scents of sewage, sweat, and alcohol combine into an unholy mix, assaulting your nostrils at every turn. Grease and oils cover the walls, turning the stone unhealthy shades of yellow and grey.
Finally, one tunnel opens into a large chamber. A mangy, flea-ridden hunting dog growls at you warily as you enter, a thick, wrought iron chain keeping him at a safe distance. A throng of shifters, humans, and various goblinoids congregate at the center of the chamber. In front of them, various pieces of junk and garbage are displayed on rotting, maggot-infested blankets. A small goblin held aloft in a chair calls out to the crowd. "No pushing! No pushing! There's always plenty of room for everyone in Smallweed's Market!"