Other lamps/light fixtures can be used too. Think outside the box. Lamps can be tilted, laid down, or hung. I certainly would not go to town just for "appropriate" bulbs. Be safe.
Your husband is incorrect. I've been using smaller bulbs for years as I often have just a few chicks that don't need the great amount of heat generated by heatlamp bulbs.
A regular bulb will work in the heat lamp if it's like the ones I have. Use a wattage that conforms to the amount of chicks you have. I have eight chicks under a 20 watt. Be careful to raise or lower the lamp to get the right heat.