Ask yourself this:
You're lying under your car and have been for the majority of the day removing bits to get to some torqued bolts. It's a pain in the arse, you're filthy, cold, hungry and cranky because you haven't eaten and you've smashed your knuckles way too many times. You have a few hours left before you can relax and you have to torque these bolts up. Would you want to risk doing it with a cheap wrench and potentially ruin the thread or not tighten it enough which means you could end up doing it all again, or would you rather a more expensive unit, with peace of mind that it'll be ok?
This is of course a rather extreme example but it's what I always ask myself when buying tools of this nature.
That said, I've used some Sealy stuff in the past and it's been fine.