So, I am guessing that you are planning on getting those specific items? Your local REI (you live in Washinton, so there are a bunch of stores) will actually have cheaper prices. Go there and RENT as much as possible. This would be your pack, tent and bag for sure. Maybe even a stove. Now, lets look at some of your specific items.
The compass.....that compass is a really nice compass. I have a similar Brunton one that I paid $50 for at REI. I love it, but I also know how to use all the features. Do you? If not, then I would look at a much cheaper compass.
The big knife....I sometimes carry a big knife. It has it's uses. But, those uses are few. Do you know what you would use it for? Can you do that type of activity where you are going? Most cutting tasks are better accomplished with a small knife, or better yet, scissors. The SAK looks good, but if you don't know why you would use the big knife, then don't carry it.
The filter is a great filter, but it is bombproof and meant for expeditions. You can probably RENT a filter from REI or buy one of there other options. Most are between $50 and $100, not the $280 that the filter you show goes for.
If you bring a jetboil, then you won't need a separate cup.
I have used Datrex bars before. They serve a purpose. I would look for the mainstay bars that only have 3 bars in the package. It counts for 1 meal. It takes a special type of person to eat those willingly. I would try it before the trip.
You shouldn't need replacement batteries for a three night trip. However, just bring enough extras for one replacement. If your flashlight only holds 3 AAA batteries, then only carry 3 AAA battery spares.
You don't need a full roll of tape. I take a piece of plastic (think credit card size) and wrap a bunch on it.