You may want to save up more if your budget right now is only 500...
Usually beardies cost from $50-400+ depending on genetics and morphs. However its more common to find them at 100 at the very least in my experience.
I paid 175 each for two eldest from a very good local reptile store, the males a citrus hypo trans and the female is some sort of red color phase, I've been told either a fire tiger or a rainbow tiger... however we have no idea if she's het for anything.
Setup is a bit expensive but if you just get an adult setup from the get go you'll be fine on that part, however if you upgrade it you're looking at a very expensive process.
75 gallons is what I consider the minimum, it provides the space they need along with the height they need and it also provides more options of basking spots and UVB levels that a 40 or 50 gallon doesn't.
Usually 75 gallons are around the same amount as a 40 or 50 gallon that has front opening doors, however during the petco one dollar per gallon sale their only around 97 dollars instead of 200+.
Getting the fixture and
UVB bulb at first will probably be around 100 or so.
Generally you want to cover half of the enclosure with a tube light UVB at the very least, however I prefer a 46" over my 75 gallons rather than a 36".
And then of course you have to replace that
UVB bulb every 6-12 months.
Substrate is probably the least expensive part of a bearded dragon as you can use tile, paper towels, or non adhesive shelf liner (these are the main three good ones).
Oh and of course the lid for the 75 if it doesn't come with one will be 30+ unless you make your own.
And then the basking bulb, fixtures for the heat lamp, the decor ect really depends on what you buy or where you get it from.
Food is probably one of the most expensive parts of a beardie.
Your probably looking at 20-40 dollars every two weeks for a young one if you use crickets, you can save a bit of money by buying multiple feeders as that will last a tiny bit longer. I just spent about 65 dollars on crickets, and then two sizes of superworms (large for my beardies, and then small for my leopard gecko.. these are mostly treats for the beardies). If I'm buying all the feeders I give them at once I'm looking at food costs way over 100 but that will usually last me about a month. I do have 7 reptiles in total plus a worm loving hedgehog so that does factor in a bit...although the tegu and the snake don't eat insects. Well...the tegu does but she's a picky brat that only likes hornworms and dubias.
And then of course vet bills are about 100+ each time you take a beardie to a vet (depending on the vet). Very costly animals...
Just to give you a general Idea of basically a standard bearded dragon enclosure here is my youngest female in her 75 gallon.
Still need to fix the basking area with more logs so she can get higher if she wants.