Ven Vinder, the town chandler, arrives with a small cart.
"Heard you plan on scaling those cliffs at Thisletop. Well, that's a rough one. You might need some rope and whatnot. If you need anything I got here, help yourself." He nods gruffly at everyone in the group, except for Rig, who he glares at momentarily.
Within the cart are coils of hemp rope, grappling hooks, pitons and hammers, torches, lanterns, flasks of oil, and candles.
You can basically take as much of that kind of stuff as you can carry. I don't want to bother with figuring out how many copper pieces you spent on torches.