New Chair Help!

So for X-Mas I was given some money and I wanna buy a New Chair because right now my ass hurts! So I have about £80 / $100

Now It's gotta be really comfortable and have a swivel and preferably a rocking function. The best I found as yet is this:

https://www.amazon.co.uk/Office-Leather-Computer-Gaming-Adjustable/dp/B00ABH5NLI/ref=sr_1_8?ie=UTF8&qid=1483218360&sr=8-8&keywords=comfortable+swivel+chair+gaming

The colour doesn't bother me It's just gotta be comfortable and have high adjustment not those bean bag things

I also wonder what are you guys sitting on? Ma Di...

Please Help! Just spam me with links it's all good!