Making your own displays is one of the best ways to get the features you want and lower the cost of setting up your booth.
One of my favorite methods is to find an appropriate unpainted wood piece available at most craft stores, paint it to the color I need and add any easel stand pieces I need to.
Paint is very important when working on display pieces, as the wrong kind of paint can ruin both the project and the jewelry that later is on it. Stay away from using artist's acrylic - even when dried it tends to remain very flexible and can easily be marked or adhere to something laid on top of it, causing stacked displays to stick together or paint to come off on your jewelry - the worst nightmare of all!
One of the big things to remember with any paint is that even after 24 hours when you can touch it and it feels dry, it's still soft inside. There are paints (like artist's acrylic) which can actually take months to dry and shrink completely but seem dry within an hour or two of painting. Because of this, all paints can be scratched, lifted and hold an impression until they fully cure. This is why I always recommend putting painted objects in a protected place, shielded from dust, for at least a week. Two weeks is better, or as long as possible.
I also recommend using at least two coats of your chosen paint. Wood is porous and will absorb some of your first layer of paint, occasionally it will even absorb some of the second layer. It is a good idea to sand the bare wood, put down your first coat, and then sand again to remove any rough fibers that were raised by the absorption process. Then add your second coat and if it does not dry smooth sand lightly again and recoat. This won't be an issue with metal assuming you use a smooth piece of metal, but it's a good idea to clean and sand metal before painting to help it hang onto the paint.
For wood, interior/exterior latex - IE paint you'd use on your walls - is what I always use. It's awesome because it's as easy to use as acrylics and washes with water, and it dries pretty tough. This is the kind of paint you'd use to paint furniture, and so it does the best job of tolerating things being placed on top of it without marring the surface. You can get it in gloss, semigloss, eggshell, etc, and they have small sample jars that you can have mixed with any of the bajillion colors available for wall paints, so you can match it precisely to your overall color theme. There are also pint and quart cans of pre-mixed colors that are usually in the basic colors and sometimes a variety of sheen's. These usually run less than $10 per color, and a single can will go pretty far.
For metal, I prefer Rustoleum. It is strong enough to stand up to outdoor conditions, but it is an oil based paint and will require paint thinner to clean the brushes and you should paint outdoors or use ventilation.
Another note is depending on humidity, paint can take longer or shorter amounts of time to dry and fully cure. The paint you choose should tell you how the humidity will affect the paint.
Once you've painted your display piece and allowed it to dry thoroughly, you can proceed with making it function the way you want. Some options are adding an easel back (or placing it in a free-standing easel), drilling holes and inserting posts or wires to support or adjust the display, or gluing a few pieces together to change the overall shape or function of your piece.
I enjoy taking old photo frames, painting them and attaching fabric mesh or perforated plastic to the back and then adding an easel back to it to help it to stand. These are perfect for hanging earrings on or adding hooks and hanging necklaces.
One last piece of advice would be to paint all of your displays the same color in order to give your booth a very cohesive feeling that won't overwhelm the lovely colors of your jewelry.
Remember - a cute display will leave an impression as a cute display, but it's your jewelry that should leave the impression, the display should disappear!