Need help - big computer chair

I need help finding a big computer chair Preferably under $500.00.  I 
currently have one but even in it's lowest position (the seat is about 18 
1/2 - 19" off the floor), it's too tall for me (it's perfect for my
husband 
though).  I do use it anyway with a foot rest.

The problem is now that I've purchased a wood floor mat (got tired of 
buying the plastic ones), the chair really slides and when getting in &
out 
of chair I have to be real careful.  Yesterday the chair slid out from 
under me as I was going to sit and I ended up on the floor.

I'm about 5' 4" and I need something that's a little shorter.  Looking 
around the web it seems that most of them are around 19/20" at the 
shortest.

I do have a 2nd computer chair in my office (it wasn't rated to handle 
large people but I have had it for over 10 years now).  The problem with 
this one is that it no longer goes up and in it's lowest position it's 
about 15" off the floor.  Now I can deal with that, although I would like 
it a little higher.  The problem with that chair is that the arms are 
permanently attached and don't move and they cut into my legs making it 
uncomfortable to use for any length of time.

Anyone know of any web sites where I might be able to find something?
Lisa