Do fast turnaround on proposals. Try to do them in one day. This is possible if you create a proposal template with the basic format where you only need to fill in the specific objectives, methodology and measures of success. It should take no more than two or three pages. If clients ask if you can lower your fee for a project, never unilaterally reduce the fee unless they are willing to reduce the value of what they receive.
People love to reduce fees but hate to reduce value.
Hold your ground. Give your clients a choice of yeses. Most people will choose the standard package. And they'll often upgrade to the deluxe. Adding value to your services alters the perception of cost.