You can hire an H1B for 45k/year. I know because I was that H1B at one point. My previous employer gave me quick pay rises once I proved that I was capable, but not everyone is so lucky.
This was for a programming role in New York City- I do not know anyone that gets paid $45k. I'm unsure how they calculate prevailing wages, but I'd suggest that the formula could do with some tweaking.