There is so definite values that go with each number. As many of us have said before, the dollar signs are terribly inaccurate and really shouldn't be used as a true guide for what venues you can and cannot afford. Your best bet would be contacting the venues you like to get their pricing. Good luck!
Absolutely don't use that as a guide. I just finished my venue search and I can tell you that there seems to be no rhyme or reason to the signs. They also don't consider what is included with each venue, food and drink minimums, etc. You're better off calling or e-mailing for package information. Most of the venue representatives get back to you pretty quickly. Or ask here...lots of people can give you an idea of whether something is within a specific price range.
In The Knot magazine they have the symbols and what they mean.
$ = Inexpensive
$$ =Affordable
$$$ = Moderate
$$$$ = Expensive
I wouldn't go by this though. I'm just starting my venue search, and the couple we found in the magazine that said "Affordable" were way out of our budget! I agree with the other posts, email or call the places you're looking at. They'll be able to give you a better idea of price.
Re: Venue Pricing Legend
Married February 20, 2011
$$ Affordable ($601-$1500)
$$$ Moderately Expensive ($1501-$3000)
$$$$ Expensive ($3001-$5000)
$$$$$ Very Expensive ($5001 and up)