I bought an inversion table earlier this year. I got a cheap one but my Pilates instructor has the Teeter brand which is one of the best ones available in New Zealand.
Some things to consider when buying an inversion table:
The foot supports - some inversion tables come with leg cuffs front and back, some with cuffs just at the back and rollers at the front and others with rollers front and back. The Teeter my Pilates instructor has and the cheap one I bought have leg cuffs front and back. To me these seem more secure than rollers. I also wear thick socks and shoes with mine to make it more comfortable and secure.
When you are first starting out with inversion you will not want to go fully inverted and will need to restrict your degree of inversion. Some inversion tables, like the Teeter, use a strap for this. The one I have uses a locking pin system that allows you to lock in at a 20, 40, 60 or 80 degree incline, or you can remove the pin to go fully inverted. When I started I found that 20 degrees was enough and after a while was able to progress to 40. I have tried 60 but the rush of blood to my head is too much so I am currently sticking with 40. I still get a good spine stretch at this incline. If you get one that uses a strap system you will need to make sure it is adjusted and connected before you get on the table.
You need to get your height adjustment right as these tables work on your center of gravity. If you set the height too tall you will not be able to invert and if you set it too short you will invert and not be able to get upright again. Another good reason to restrict your inversion angle until you get this right. Also look for one with good side handles so you can pull yourself back upright if necessary. Because my table is a cheap one it hasn't been properly calibrated for height, I am 5 ft 3 but when I set my table to this it was too short and I had to use the handles to pull myself up, luckily I was only at a 20 degree incline. I actually had to set it to 5 ft 5 to get it to work right.
Hope all this helps.
Hazlady