birdman don't go out to diner next weekend and no Starbucks this week and you got your filter. Small sacrifice big payback.
+1 Why would you spend $1,000 on a lens to dump on a cheap $30 filter? Filters do make a difference. That doesn't mean you have to spend $300 on them though. I tend to stick with the higher end Hoya line (HD line or the dmc pro1 lines) and have had good luck with them. I really Like the HD line with the hardened glass - it cleans a lot easier.
For grads, Lee, B+W, Schneider are all great. I had a Lee once, then broke it. $250 down the drain. I have used Cokin and have a ton of "A" filters that I almost never use. They are cheap. The ZPro & XPro Cokin filters are actually fairly nice. The one thing I have noticed with plate grads is that to do it right and not get reflections bouncing between the lens, filter and plate filter, you do need the Hood made for them - which is huge, and a pain unless you are specifically going out to shoot something in particular. If you do it right, they are great - If it is haphazard, so are the results I have found.