Have a look at the Manfrotto range. Vinten and Sachtler are part of the Manfrotto group anyway and most of the legs are made by Manfrotto then given a different lable.

My personal advice is not to go too big. If it's heavy and bulky you'll be less likely to schlep it around. For a PD170 and bits the 501/745 kit I have is more than up to the task and I've used BetaSP kit on it without any problems. It's at the top end of your budget but I'm a bit wary of getting used heads having had mates who have been stung when they've bought second hand.

The point is that a used head may have a couple of sticky positions which you won't notice when you buy it, no matter how carefully you test it. It's not until you're doing a really slow pan with maximum zoom, then you realise why the bloke sold it. If you're not worried too much about weight then you can also pick up the superb 116mk3 heads at a good price at the moment because Manfrotto's bought out lighter versions and the old stock isn't popular. Big but smooth. Bit like me really.

I've also got a 540Art/510 kit which is loverly. Okay it's expensive but I really can recommend it. I use Vinten and Sachler daily and they are good (obviously) but the smaller ones are just re-badged Manfrottos and second hand can be dodgy in my opinion.