On the higher end, Marumi filters are really quite good - if you need a really good ND or polarizer and don't want to monkey around, they're excellent filters and less costly than US or Euro name brands. I expect they'll be a respected manufacturer before long. But if you need a specific screw-on size, look at used offerings first, the market is pretty flooded.
I shoot digital video for a living, and I use a 4x4 matte box, so filters can be exorbitant (but also a lifetime investment). I've tested extensively, and mid-level chinese resin filters have no sharpness or distortion hit when compared to Tiffen glass filters - and I've pixel-peeped the heck out of this. Where cheaper filters fall down is in things like heavier grades of ND, where color casts can be an issue. No biggie with digital or B&W shooting, but for color film it could be a real concern. (I've tested by sampling RGB values with raw photos, and with cheap filters, they really can swing into the blue and green realm). If you need consistent color, spend a bit more, and remember to test anything you purchase.