UVB light fixture question. NEED HELP?

ok so im planning to buy bearded dragons soon and i want to get everything ready before i get them. so i am getting an 18 in UVB bulb for them but the only problem is that i need the fixture that holds them. all of this is coming out of my budget and i am only 15. i want to save some money and hopefully get a cheaper fixture. so i found a black light fixture that is 18 inches too. so i was just wondering if a UVB bulb would work with a black light fixture. i dont want to harm any animals so should i just spend the extra money on a fixture or get a black light fixture. please let me know what you think, thanks.