If you're short on money I don't suggest getting a bearded dragon at all, they can become expensive to feed considering how many tubs of crickets they go through a week. A blue tongue would probably be your best bet.
Tank setup is reasonably expensive as with 99% of herps, All my beardeds get crickets once a month, the three tubs cost me under twenty dollars, i put them in a container in with hiding spots, carots, gutload, specialized water crystals and potato.
Considering you would only have one bearded that should be enough to last your bearded just under a month assuming they get fed every second day give or take a little for cricket deaths etc
When they arn't eating crickets it's veggies and fruit which you would usually have on hand anyways just like bluetongues, shinglebacks.
It can be as inexpensive as you want it to be, but you should be generous with items like heat lamps, UV lights, cricket care, reptile cleaning agent, a calcium supplement and reptile pellet food (and all will last you a considerable amount of time) and the actual lizard it's self.
Get a second hand enclosure from the trading post or ebay, make sure it is big enough to house the dragon throughout it's whole life, and thoroughly clean it out with the reptile cleaning agent beforehand.
If you get a beardie hatchling they don't need much habitat wise, they can be kept on newspaper (i recommend spending money on good reptile substrate when they get older as their mess gets messier and DO NOT USE SAND) a few rocks and logs which can be found outside, soak them in the reptile cleaning agent, and put them in the oven, make sure the rocks and logs have no bark attached or hiding spots for spiders, spider eggs etc try and pick a nice clean cut rock/log.
