What venue of advertising do you guys find to give you the best ROI? (i.e. radio, newspaper etc. etc.)

Overall, I think that Pay Per Click search engines provide the quickest ROI, especially if you want to limit your spending. In the long term though, and I know this doesn't officially count as advertising: Word Of Mouth.

As such, I think you should concenrate on providing the best damn service you can. Make your customers really happy. Yes it will cost a little more at first, but in the long term it will mean less spending on advertising, and more happy customers.

I agree with the word of mouth. I have not had too much success with google and a few other PPC places. I was just looking around at something other sites.. this one was pretty funny:

http://www.valuesponsor.com/advertise.html

"ValueSponsor want you have a great results but only need to pay a cheap prices !"

Awesome grammar :)