Most companies that you call will give you the run around about having to have somebody come out and take measurements to give an exact price. While this seems like a ploy to get a salesperson in your home, most people would prefer to know if there were any issues prior to spending a dime on a walk in tub. I'd be more concerned with a company that's ready to take my money over the phone, having failed to ask some very important questions regarding installation. It makes sense that costs could vary greatly from one install to the next.
In my research, I've found that many of the walk in bathtubs on the market today are imported from oversees. However, there always seems to be a battle of who's tub was made where and why it's better, no matter which company you call. You just have to ask yourself, is it important to you to have an American Made Walk in Tub? From a quality standpoint, I personally wouldn't have it any other way. The problem with buying American Made products (as with anything else American Made) is typically the price point.
Walk in Bathtub Comparison...
It's important, no matter what brand you choose to go with, read the warranty in it's entirety. Many of the BBB reports filed against Walk in Bathtub companies has to do with Warranty or Service issues. You'll know that you're comparing apples to apples only after you've full compared warranties.
Pricing and Negotiation...
Safe Step Tub dealers may have a new tub from a canceled order sitting in their warehouse. This could be of great benefit to you, especially if it's the right size/direction/color for your bathroom configuration.
If the cost with installation is too steep for your taste, make sure you ask what all has to be done to have the walk in tub installed. See if there are any steps you can complete yourself to save some money, or maybe your son-in-law is an electrician that can wire it for you!
Though I don't have exact figures on the Safe Step Walk in Tub, most quality walk in bathtubs are typically between $6,000 - $15,000 before installation, depending on the size and configuration.