Agreed. Some of the outfits slip the camel's nose under the tent; suggesting that's all there is to it. Then, once you have agreed to it, you get the full disclosure... addresses that are 5 miles outside the city limits on a dirt road; or a VA signing with 200 pages, etc.
Plan on the worst when you make your counter. If the number of pages is not disclosed, assume 150 and quote for it. Calculate the miles to the center of town and add a few more miles in your estimate. No mention of scanbacks? Add $10.
Maybe itemize all that in your counter.
Finally, don't go below your minimum; unless you know EXACTLY what it will cost you. For me, that minimum is $85; soon to go up now that I have 25 signings under my belt. So don't ignore those $30 offers, decline them and counter for $100. Or $125.
That's when the negotiating begins!