Good cheaper filters

The filter is cheap and came well packaged in a filter box here. Delivery Time 1 day. Super!
Almost all ND filters have a certain strength from a color cast, of blue, purple and yellow-brown is because everything here and with me it tends toward yellow-brown.
A gradient, however, I can not determine, but that happens quickly when the viewfinder is not covered by prolonged exposure time and thus also the light can "interfere with" the sensor. This results partly right ugly stripes or patterns that are too bright or dim, or mushy. With some cameras, you can close the viewfinder, cover with a cloth or otherwise - often the strap - with a kind of close lid. Also, a second filter, for example, a UV filter, the use a lot as a lens protector, reduce the quality.