ah! not being able to try out chairs will make it more difficult! I agree it is a lot like buying a bed, everyone has their own idea of what is comfortable. I unfortunately can't give you any good suggestions for chairs, I am currently sitting on cheap - back ruining variety. Im also sorry if I offended anyone, it was not my intention, I saw a humorous picture of a chair and could not resist firing off a pun.
Good luck on your hunt for a comfortable chair! And for what its worth, I agree with K C, while there obviously has to be some balance (i.e dont go and buy a $3000 chair with a built in back massager (even though that would be awesome)) more expensive chairs will tend to be better designed and last longer, allowing your back to stay better designed and last longer!
Jeff
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