At $20-$30 a month on coin-op laundry you are probably better off looking for full-service laundry that charges by the pound. Before I moved into a place with a washer/dryer of my own I was spending ~$10-$15 every two weeks (50 cents per pound) to drop a laundry basket full of cloths in the morning and pick it up perfectly folded later that day (took about 4 hours, but I would pick up in the evening).
full service laundry in new york city is always at least 40% more money than doing it yourself - which is logical since it's the price of the machines plus the service. I believe you might be comparing two different areas.
edit: some googling reveals 85 cents a pound is the cheapest and most are 90c-$1: http://centzy.com/nyc/laundry-10024 so about $20-$30 for your size of load, guess our loads are bigger.
Hmm, the cost of doing it myself (at the same place that did it for me) with coins, plus the cost of detergent, worked out to about the same price as having them do all of it. I assumed that cost of full-service and cost of machine-time and detergent would more or less scale together.
