In this day and age you can order from anywhere promptly. I ordered a part from the UK and received it in 5 days - including a weekend. GenuineDealz is prompt as well and when I purchased my battery cable crimpers from them they arrived in a few days. Both of the above had to cross borders so I look at time frame as a bit of an excuse.
I would think if you just crimped properly and used adhesive heat shrink that the moisture would be kept out indefinitely. It works several hundred feet down a well so should also keep moisture out in a Catalina 22. Tinned is better but most 30 year old boats do not have tinned wire and are still functioning.
Living aboard in Victoria Harbour