A bit of a book about shoes!
There are only a few things you need to look out for when buying exercise shoes.
Do you want shoes or boots? - Boots give more ankle support but can be more restrictive and are usually more expensive.
Whichever you get you should look at the soles first. The flat part that goes under the ball of your foot should be flexible. It should have 2+ lines/scores acrros it to allow it to flex with your foot. Tennis/running shoes don't have these.
The foot and heel part should be properly separate, with some obvious support for the arch of your foot. This means the sole should not be flat but should be contoured.
The back of the heel should have a notch in it. This allows you to point your toes without putting pressure on your achilles tendon. May not sound important but it is the main cause of pain and injury in the ankle after a workout!
You should be able to find a good pair of shoes/boots without having to break the bank. Remember even the most expensive are only designed to do a couple of hundred miles before wearing out (less than 6 months @ 2 classes a week).
Never ever wear you shoes outside of the studio you workout in. Firstly you track in dirt and stuff! Worse you wear away the soles of your shoes. The rubber on them is really soft and is not designed for tramac, flagstones etc.
I won't recommend a make cos everyone's feet are different. But if you haven't found a comfortable pair yet: I personally wear Nike. Very expensive but they fit my feet whereas Adidas, Reebok etc don't. I think this has to do with the re-sizing they did about 6 years ago. If you look inside the shoes they have a big W that says they were engineered for women athletes!!!!! What this means is the ankle is narrower and the foot bit is a different shape too. Does for me, but as I said, theyare expensive. I can afford them because, as an instructor, I can write them off against taxes!
Hope this was helpful, Stef.