I second the hotel sink option. I'm not a fan of hanging out in laundrettes.

Aside from gel, detergent is available in bar form, just like soap, and you can buy it virtually everywhere.

Fill the sink, soak everything, scrub with the bar. Drain the sink, fill with clean water. Rinse out, squeeze out, repeat until the water is clear. Squeeze out as much water as possible and hang out to dry. It doesn't take that long and it's cheap ^