Worth paying for is a tricky proposition as everyone evaluates that equation differently.
There's a Rosle set I'd love to have. I judge it as not worth the price based on my needs and personal economics, but it's wonderful piece of kit.
The food mill I do have is an inexpensive Martha Stewart brand. And it's served me quite well.
Of more importance is if the one you're considering is built well enough, and has disks that fit what you want to do with it. I wouldn't use mine to remove raspberry seeds if making jam, but I don't think I've seen one that would either. Also spend some time looking at how you'll suspend it over the pot or bowl. The Martha Stewart one won't fit really big pots/bowls but one that would would be difficult to store as well. Do they put any effort into limiting slip on the supports when in use? notches?
And just where will you store yours? Mine's not in my kitchen at all, but I'm still glad to have it.
There are plenty of pretty good models that range in price between $18-30. The pricier models tend to have more interchangeable blades and have a larger holding capacity. As Phatch mentioned, take a look at how the mill will rest over a bowl or pot. It can be frustrating to use a mill that moves around or is wobbly. Also take a look at or ask the store clerk about how easy the mill is do disassemble. You will need to do this to clean it properly. Happy cooking!
I really like this mill, it's an Oxo. I got it with a 20%-off coupon at Bed Bath and Beyond for $40. It has three different blades and seems to be very well made. I've used to make some awesome gnocchi, tomato sauce, and puréed soups; it does very well at separating out peels and such. I'm using it more than I thought it would, since the texture it gives to purées is nicer than what a blender or food processor would give.