First question I have is where are you advertising that you can get those rates!
For me a $65 quote for radio in Chicago on one of the top FM stations would be a darn steal!
And I have to say I have run into the same troubles that you have, crazy swings in prices and no way to really be able to tell who is giving me the straight talk. Which muddies up the question of if you are getting a "good rate".
In my opinion, a good rate is something that fits in to what I can affor (of course) and is competitive with what other media reps are quoting me. I think calling a few of them was a good move on your part, but also showed you that you are working with some real slime balls.
"Real" advertising price is what I'm going to assume you are talking about when you also mention the wholesale rates these guys buy. No way you can get it for the wholesale rate - but you can find some great websites that show you what the average price is for different stations in different states and different times (you can do a quick google search and find all sorts of results that work.)
Starting your own advertising business is a move you can make in SOME cities. Look at what happened to google when they tried to get into radio advertising...things didn't go great and they shut down out around $200 million bucks.
Reps "laying claim" is more of a professional courtesy than it is a rule in most markets, there are exceptions - where are you from by the way?
The hardes part about finding a media buyer is...finding the media buyer
Honestly it isn't easy, but google is an amazing tool when looking for a company that you can trust. I did this, found one that I was happy with, I just couldn't ever find the rates and found some really nice internet radio sites that are giving me the "juice" as they say.
Radio advertising is tricky, that's why so many traditional media outlets are starting to die, they don't have the pricing that their internet radio counterparts do - who happen to have better tracking tools to calculate ROI much easier. you can even sort of calculate what sort of brand recognition you are getting on internet radio, and not traditional radio. Again, a reason that advertising on radio is very tricky business, more effective of course, but also very tricky.