Normal bearded dragons and even some colored dragons at the majority of petstores will be marked up 2 x or more of what the petstore paid. So if they paid $20 for the dragon they will sell it for $40-$80. Local reptile shows or shows close enough to drive to and local breeders and breeders within driving distance is the best way to go. However, keep in mind not all breeders are good breeders but usually you can tell who are the good ones by seeing the health of the dragons they have, their setups, how well they can answer questions etc.
A reptile show is best as you don't have to worry about shipping, can see different breeder's dragons and prices and get the best value for your money. It also gives you a chance to get other equipment you need, especially crickets for baby dragons (they do go through alot of crickets when young, so getting a box of 1000 pin head to quarter inch crickets (depending on the size of dragon you buy) at the same time saves you money. Just have a bin to put the crickets in so you can feed them well before feeding. (rubbermaid containers with a hole cut into the lid and covered with aluminum screening works well).
At a show I went to recently, they had nice neon yellow stripped baby dragons for about $125 or so (Canadian) which I was tempted to buy but didn't as I didn't have the tank space for them at the time. There were less colorful dragons available for less than that and normals can sell in the states for as little as $10. If you don't mind a bit of aesthetic mars, you could talk the breeder down in price for a dragon with a nipped tail/toe (providing the dragon is still healthy, the injury isn't swolen or otherwise looking bad). Sometimes if you are at teh show near closing you can get deals as breeders usually would prefer to lower their prices than carry the dragon back home. Of course there is always the chance the selection would be poor or non existant, depending how sales here.
Shipping a dragon to you from a breeder is another option but sometimes, driving to pick up the dragon is cheaper depending on distance. Comparing how much it costs you to drive to the breeder and back and what it would cost to have to shipped to you, is something you will have to consider. If you don't have a car, well driving is kind of a mute point.
The biggest espense for dragon ownership will be keeping a steady supply of crickets till the dragon reaches adulthood (roughly 12 months) and by then you will be feeding mostly greens with only small amounts of crickets and other insects. The next big cost wil be the adult cage. If you are handy with building things, it is cheaper to build your own cage. If you can't build anything if your life depended on it (grin), then finding a friend who can and is willing to do it, could be a good option (besides, friends typically are very happy to do it for small reward, case of beer, free dinner at a nice restaurant, tickets to a ball game, movie etc. It's your friend so you know what is good to bribe them with LOL). Just supply cost of wood etc, and usually they are happy. Retired people who like to build things are a good thing too, sometimes they just like to have something to do and building a cage makes them happy 
(it's how I had my cage built, family friend is retired, loves to build things over the summer. Bought the wood I needed, brought it over, when I picked up the cage, gave him a bottle of booze. He was very happy to get that Pitty he lives too far from where I live now, else I will commission him to build me a few more cages).
To help cut costs, buy fixtures at a hardware store, not the petstore. You will pay more at the petstore every time. Unfortunately the only thing you have to buy and can't get at a hardware store, is the UVB bulb. Most online mail places have them cheaper but then again, look into how much shipping costs and determine if it is just as cheap to get it locally. (then again, you can buy it at the show same time as the dragon). Basking bulbs can be bought at hardware stores, just typical household bulbs work fine (the coiled florescent tube lights don't put out enough heat to be used as a basking spot,one reason why they are more energy efficient).
Bowls, hides, cage furnature, can be picked up in many places to reduce cost, other than the petstore. Ceramic bowls from a dollar store (those 3"-4" wide, 2-3" hide ceramic pots work good), small to medium sized plastic flower pots, with holes cut into them can serve as hides. Plastic plants can serve as cage decoration. Plastic table cloth rolls or non stick shelf liners make great substrates.
Home hardware type stores is also a good place to get bricks, slate tiles etc for realy cheap or free, if you ask only for a few already broken pieces. Tiles and bricks make good basking spots but have to be set up securely (putting some 5min epoxy between them helps to stablize them) so they can't fall down and possibly injure your dragons. Also make sure they cannot dig underneath them as well.
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PHLdyPayne
