Well I think you got some good answers there, but I'll leave my input
My beardie, Mojo, I only got on Saturday the 19th and spent most of the year I did saving and researching trying to figure out the prices etc. I knew that most beardies don't touch their salads as young as my dragon is (about 2-5 months, not sure yet) and that he would be stressed in his first week, but oh no. Mojo was an eating machine that doesn't stress about anything. He needed top ups on his salad as he'd eat the whole thing and has been eating about 10 crickets/hoppers/roaches per feeding. He ate 20 crix once but that's because they were tiny ones.
So I bought a pack of crickets at the reptile shop and they always give free bugs to start you off with your new pet and they gave me hoppers (which I'll never be buying again due to the amount they jump o_o)
I then ordered 250 crickets and 50 roaches that came on Tuesday and the roaches were gone buy Thursday =D There's about 10 of the tiniest crickets ever left but I bought another pack of medium ones at a pet supply shop.
He's on his seconds bag of greens, but had to chuck away the rest as it had gone off. You can leave a bit past the expiry date, but as soon as you notice it kinda wilting, bin it. I do that with Mojo and my rabbits (as they eat the greens too).
So I spent about £10 online for bugs (250 crickets and 50 dubia roaches) and £2 for that first box of crickets and then £2 for greens and grated carrot at the beginning of the week. My mum ordered in butternut squash which is high in calcium but she said she'd buy that. If there is anything in the fridge that is safe for beardie's, I'd just cut some up and add it to the salad. Varying the diet is always better. I do add some Juvenile pellets on top as well just for extra stuff which Mojo takes up when eating greens.
Buying bugs online in bulk is always better as it's cheaper. I found I site you can get 125 crickets for £2.30, the same price they sell about 20 in a pet supply shop. The site was called Rick's live food, or something like that. My parents said that they don't want insects breeding in the house, which is fair enough, but that is pretty much the cheapest way (except you need to buy the food for bugs etc)
So per week:
-£12 on live food
-£2-4 on salad (depends what else you buy) I use Spring Greens (called Collard Greens in America) as they are high in calcium, a little bit of grated carrot and this week I used butternut squash.
-Total = About £14-16
Roughly every 2 months I guess (depending how much you use)
-£3 on Bug Grub
-£3 on Bug Gel
-£3 on Reptile cleaning disinfectant (maybe 3 months on that)
-Total = About £9
Get new lights yearly about £60 (or £40 for MVB which I will use until Mojo grows and needs a bigger vivarium which costs about £70 - £100, although the one I have now was £20 as it was second hand and I may be making the bigger one)
So every month for food
Roughly 4 weeks in a month.
Round 14-16 to £15
£15 x 4 = £60 per month o_o just realised that lol
Then every 2 months for food and the bug stuff and cleaning stuff
£60 x 2 = £120
£120 + 9 = £129
So about £130 every 2 months
Every year, 130 x 6 = £780 + 60 = £840................. .... they are very expensive pets =D
Sorry this message was preeeetty long, but I wanted to leave my input ;]