My last fill was $28 for a #3.
The last time I had praxair fill my dad's #4 it was $70 (and that was a few years ago). The bigger chains keep jacking rates because they only have the blue rhino extortion to compete against. If you shop around, you should be able to find a smaller shop to give you better rates and better service as well.
My LWS is actually a sole proprietor who buys his fills off a competing (much larger) vendor. But even buying the gas from another store, he can sell it to me for less than they're willing to sell it to me direct. He also doesn't add hazmat BS, or even charge for hydro tests - he considers them part of his cost of doing business. You pay for hydro on the tank the first time you swap it (if it's due or not) if it's a used tank you bought from someone else, and never again.