Congrats on the M3! Tbh that camera is a beast but yeah, those old lenses flare like crazy near water. You definitely need a hood if you are shooting in Seattle. Honestly, you dont need to spend 300 bucks on an original Leica piece of metal. Thats just crazy talk when you are starting out. I would suggest being a bit cautious with the super cheap plastic ones from Amazon tho... they tend to look really tacky on a classic camera and sometimes they block the viewfinder more than they should. Since your budget is around 50 bucks, you can actually get some really nice third-party metal ones that look legit. I personally use the Haoge LH-M36B 39mm Screw-in Vented Metal Lens Hood on my 50mm. Its vented so it doesnt block your rangefinder view too much, which is a huge deal on an M3. You might want to consider that one because it feels solid and matches the vintage aesthetic. Just make sure to check your filter thread size first! Most old Leica 50s are 39mm but some differ. If you want something even cheaper that still works, look at the JJC LN-39S 39mm Screw-in Lens Hood. Its basic but it gets the job done without ruining the look of the kit. TL;DR: Grab a metal vented hood from Haoge or JJC for under 40 bucks. It stops the streaks and wont look like a cheap piece of junk on your shiny new Leica.

Seconded!