I like Google Adwords. Hand down its the best online advertising system out there.
If you are in a market like my market, which is the postcard printing market, then it becomes almost impossible to get on the first page of google for the best keywords... and even if you are on the second page, there is still 10+ competitors in front of you absorbing the market.
Now in my company's case, we have industry competitive pricing, and we lead in pricing for quantities of 20,000+, but this DOES US NO GOOD if we cant get exposure.
So what adwords does is, if we can afford it, places our ads on the first page on the right hand side. And people click! And we convert!
We pay per click, "impressions" which are ad renders, are free.
So being the administrator of this advertising department I can tell you that the majority of out sales comes from Google Adwords. And we pay for it... but when we secure a repeat customer that prefers our business, then that cost was well worth it.
This strategy can be successfully replicated for your cleaning industry if you have a nice website that funnels your sales appropriately.
Another reason to get a website huh!? In the mean time my company has amazingly low postcard printing prices for your already proven direct mailing campaings.