It all depends on your requirements, your budget and your preferences.
You can get wooly covers from the likes of Autobarn and SCA, you can get cheap shit from ebay, you can get overpriced canvas ones like black duck sell and you can get overprice neoprene covers. It all depends exactly what you want.
Jsut make sure you get airbag compatible ones if you need them.
So are most of the canvas one. Try a search (or and advanced search is better) for Black Duck or black duck seat covers, I'm sure the topic has come up a few times.
I have black duck canvas ones on mine, I purchased them less than half price off ebay and I like them.
Not sure I could say the same if I payed full price they get sweaty on hot days etc.
I have black ducks as well which I bought of eBay second hand. Got front and rear for $150!! Rear are brand new, front had been washed by previous owner and got a funny colour. I just dyed them dark grey and all good.