I suppose it depends on what you consider the average person - it's not available for free, but it is available as part of the $20/month ChatGPT Plus. I suspect $20/month is very affordable for most HN users.

ChatGPT Plus is very bad value vs ChatGPT API (particularly now that 3rd party chat clients exist)... I've spent $20 on ChatGPT Plus in the same month where I've spent < $1 on the API and used it significantly more via my github bot.

My subscription is due for renewal this week and I was going to cancel it, but for me it's worth it short-term for GPT-4 access. The increased context size and improvements in reasoning & general output quality are significant for my use cases.

GPT-4 access in ChatGPT Plus is quite limited (was originally 100 every few hours, currently 25 and going lower since they're struggling to keep up with demand) but that's still enough to get useful results out of it currently, especially if you have built up some intuition on how to prompt using 3.5.

V4 is baked into Bing Chat. I believe paid OpenAI accounts also have access.