There is some confusing information out there regarding toads and UVB light. When I was looking up info for my setup, I found info that said toads don't need UVB light and other info that said they don't need it, but it doesn't hurt to have it. So I use UVB lights in my tanks because I figure it's a good idea to more accurately represent the natural light that toads would see outside.
The cheapest option is probably to use something like these bulbs (you can buy them individually for like $17 each or get a generic brand for less): https://www.amazon.com/Zoo-Med-Reptisun-Compact-Fluorescent/dp/B015HU2HF8
And one of these light holders to put on top of your tank: https://www.amazon.com/VIVOSUN-Detachable-Aluminum-Reflector-Included/dp/B07H8G6PKX
Or you can get a linear lamp like this: https://www.amazon.com/REPTI-ZOO-Lighting-Terrarium-Desert/dp/B08HCL4J8D
Seeing how you should use a light for your tank anyway, it seems like a smart thing to do, to use a UVB light instead of a regular lamp.
I haven't used my uv-b stuff yet since I'm not in flower but my whole setup is $30. I got 2 reptile bulbs for $20 and hooked them up to these ziptied to the top of my tent and hung down.
I have a 3 way adaptor and run them off the same timer as my light, they're currently tied up to the ceiling but I'll be dropping them down when the pre flowers start to pop up. It's like sun burning the plants, they make thc to protect themselves as far as I can understand.