I*m in the UK and got the rubber seal strips from Amazon - this one looks identical
https://www.amazon.com/dp/ (commissions earned)
Best bang for buck is a tough one - in terms of money and time/effort, the rubber door seals were effective in cutting down on wind noise, and making the doors feel and sound more premium.
I*ve cut down road noise a lot with a combination of soundproofing materials on the floor and doors, but this was fairly expansive and very labor-intensive.
I*ve also soundproofed the wings/fenders (underneath the liners) but this didn*t make a huge difference.
Next up is some anti-vibration material on the roof but I*m not looking forward to dropping the headliner...