Every good business relationship is filled with some sort of give and take, a bartering of sorts if you will. I'll provide knowledge and expertise in exchange for something else. Its natural that in business, people help people or make a barter in exchange for something. So why aren't more brides and grooms bartering in their wedding planning?
In the past few years, every magazine and wedding blog has drilled into newly engaged couples that they should negotiate and they should ask for discounts. While I agree that negotiating is a great strategy - straight up asking for a discount isn't. Why? What does your vendor get in return from giving you a discount? And, why should you get a discount to begin with? Because you're engaged and planning a wedding? Vendors are providing their skill, knowledge, expertise and passion with you in their services ... you wouldn't walk into a shoe store and just demand a discount simply because you need a pair of shoes. All of the vendors that I work with and know aren't out to screw the engaged. I hear it time and time again at consultations "don't tell x,y and z vendor that its a wedding - they'll jack the prices up!" ... um, usually not so much. Vendors know their market, know what things cost and like every other company that exists, needs to make a little extra in order to actually stay in business.
If you really fall in love with a vendor but know you can't afford their services, sit down with them and be open and honest. Flattery does help. Offering a barter or exchange may work in your favor. Do you have amazing writing skills? Offer to re-write all their marketing material. Do you have the time to come in and cut flowers for them on the weekends? Let them know. Be offering something of yourself, you're much more likely to get a vendor whose willing to give you a break on the cost of your proposal, or at least work with you to bring the cost down. Use your expertise to trade with the vendor in an area that you feel they can benefit. In everyday life, we make exchanges with people based on our needs and their needs - this should apply to wedding planning rather than just demanding a discount.
Figure out what you have that a vendor needs and then exploit it! Bartering is a years old tradition and in many cultures is the way of life - time to employ it into your wedding planning process.