I am a professional who does resurfacing of tubs, showers, sinks and many other items.
A regular tub will probably cost around $295.00 to $395.00. A clawfoot tub has a couple of extra areas to attend to in respect to reglazing. First the claw feet, secondly the sides of the tub and third a lot of people want you to spray the entire tub vs. in a home you are spray one side plus top and inside.
I would not recommend doing it yourself. Our product can not be purchased in a local hardware store.
The product can be dangeous to use because of the fumes. We use safety equipment. Also, you would neet to be an experienced at spraying. You can not use a roller or brush.
In terms of the cost. After it is reglazed your clawfoot tub could be worth anywhere from $1200.00 to $2500.00. It depends upon the overall condition, the year and make.
Check the internet for pricing of one before and one after reglazing. Also, there is a company that can reproduce one of the feet if you are missing one or somehow break one---it is very resonable to get a new/used claw foot.