Free: Contests & Raffles.
Save your money and take a trip to Alaska or Canada!
Start with the WDFW website and download a copy of the regs... read them many times over b/c some of it is very confusing.
After that head down to the local tackle shop and see if they recommend anything close to you (sorry i know nothign about your area)As far as tackle goes, on the rivers from the bank you can't go wrong with Dick Nite's IMO. Just make sure you know whether or not to use a barbless hook.... see point #1
Just PM when you want to go and I will tell you the options I'm aware of. I really like to help people that are new to the sport, especially if they are taking kids, and would like to help you succeed.
As for salmon and steelhead, go get the book "Spoon fishing for steelhead" by Vedder. Good tips on spoon fishing, but the real value is in the information regarding reading water, water temps, habitat, etc. If you want to cure eggs, get the book written by Scott Haugen. It should get you started, even if you choose to use a commercial cure.
Just to add to what wsu said, bill herzogs color guide to drift fishing is a fantastic book.
Check out some other sites like ifish, gamefishin, and washington lakes. Use the search tool, sometimes open seats are posted. Check out your local tackle shop as well. If your shorebound, this summer is a pink year and you should have no trouble finding a spot to tie into a few of those. Also check out Salmonuniversity.com. Listen to Outdoor line on 710am and NWWildcountry on 950kjr on saturday mornings 6-8am. Good luck!
This year is Pink salmon year (every odd year they return in big numbers) ,so plan on lot of fish everywhere.You can bank fish with your son for them ....just find a good river with easy access that holds the fish .We fish Puyallup river on the bank -it is mad house with lot of people ,but it's fun too . If you decide to go ,get some orange stuff now (yarn,corkies etc.) because by the time the fish starts to show up most of the supplies will be sold out ..... I got whole bunch of rods and reels .....if you need some for your kid . (they are used ,but free ) where are you at ? I'm in Renton /Newcastle off I-405
The pinks will be in the sound starting in july, they become prevelant in the rivers by the end of july with august and the first half of september being the best time. It may take them a bit longer to show in the south sound as I am unfamiliar with those rivers. As in the name "pink"salmon the best color choice for lures is pink. Cast buzz bombs from the points of the sound if you are targeting them in the salt. I like to twitch jigs and pink hoochies on a jighead when I fish them in the rivers but a dick nite and corky/yarn combo bot work when drift fished. Spinning gear is great, I use a light action rod with 6-8lbthe test. I like a light jighead (1/8 or less.) Cast out and twitch back. Typical pink is in the 3-6lb range nut they often get bigger. If you keep them, bleed their gills and get them on ice quickly for the best tablefare. The best rivers close to you would be the Puyallup and the Green. In the Puy you stand a good chance at hooking a coho ot even a king later in the summer when fishing corky/yarn. Pm me if you have anymore questions, I might be able to que you in on some other fisheries in your area.
Another idea would be to look at Puget Sound Anglers, they have chapters all over. This is more than just a salmon fishing club, the members fish for everything. PSA, is one of, if not the biggest fishing organization in the state. I am, and have been for years a member of the Renton Chapter