You do not need protective cages for use with beardies unless you are concerned that they could come into contact with the bulbs. In most cases you can position basking branches such that they cannot touch the bulbs which can save you some money. So it really depends upon your particular set up and whether your lizards can come into contact with your basking bulbs or not.
whatever u do try to make your own, pet shops are asking $40 for a small cage! i got hubby to make me one that cost about $5 lol. Just used wire framing and snake mesh I would def use one though just 2 be on the safe side.
I, myself don't find it necessary for my beardies.
As long as you provide a decent basking spot and the correct temperature, beardies are happy to bask under it.
Snakes on the other hand, I believe, will try their very best to get to the heat source as close as they can, resulting in them climbing and wrapping their body around the basking bulb.
I use them for my beardies, not because they have burnt themselves on the bulbs. I am notorious for burning my own hand on the bulbs. So now I have cages and I have not had a burn since.