My two cents on a few of those items:

• Road shoes: Pick work horses that can last for a while. As you get more into road running and racing, you'll want to diversify, as the durable shoes tend to be relatively slow, but for a limited budget you want the best bang for the buck. I personally use Brooks Ghost and Mizuno Wave Rider as my go-to training shoes. They last over 600 miles, so per-mile their price is quite low. I also get one pair in a running shop where I test them first, and later stockpile more during online sales.
• Garmin watch: Three years old isn't all that old, but there are good watches and not so good ones. I picked a Garmin Fenix 6 very cheaply (Black Friday sale, combined with the release of the Fenix 7), and I don't need a HR strap with those. If you want the newer model, look at Coros Pace 2 as well - same bells and whistles, but unbeatable price.
• Coach: After I plateaued, I just took a one-day workshop to fix my running form. You can learn the rest on the cheap, via books (Pfitzinger's Faster Road Racing is my go-to book) and then Youtube videos for more workout inspirations.
• Cap, sunglasses, tights: Even the cheap Chinese ones from Amazon last longer than the price would suggest.
• Additional expenses: As you get more into running, expect additional costs for physio or massage, or at least a massage gun or foam roller. There will be costs for sports glide, hot/cold packs, possibly energy gels or salt caps. Consumables will be a recurring cost, so budget for that as well.