How much to buy in for in uncapped games

[Ghazban]

I normally play the 1/2 $100-capped NL game at Foxwoods but have been considering trying out the 5/5 game with no cap. What is a good amount to buy in for? Conventional wisdom is that you want to have all the worse players covered but, as I haven't played the game before, I doubt I'll be able to tell who those are the moment I sit down (unless I spot some live ones that also play the 1/2). Thanks in advance.