Office Desk Chair - J Burrows or Gregory Inca

Hi

I'm looking for office chair at home ideally to sit for 5-8 hours in a day.

I found out the office works chair. I tried other day and got back pain after trying different chair felt the below one is good. So need to try again to make sure it is good.

http://www.officeworks.com.au/shop/officeworks/p/professiona…

J Burrows office works chair. Anybody used it and how was your experience?

Also i could find any store who sells Gregory inca chairs. I used one when I worked in Sydney. I want to try before I buy. Any stores in Brisbane?

I know HM is good but I don't think i can afford >1k for chair at the moment. But open to tryout if there are stores with display model to try.

Anybody has experience with Return policy with these chairs. We don't know how good it is only after sitting for couple of days.

Are there any stores who sells these chairs for more discount so I can buy after trying at stores? Is it good buy with online stores with return policy? Any suggestion and ideas ..

Thanks in advance.