Costs me nothing. Some channels eventually reach their lifetime usefulness like a topic I was interested in and amassed some 500+ mentions of it on twitter, business news from 8 months ago about someone getting acquired etc. I can export the messages and delete the channel to avoid history archival. Only real cost would be the one or two times a year maintenance and improving bits and pieces every now and then.

I think the better question is how long did it take you to set this up initially?

Right, I started with RSS initially. It wasn't in one go, it was over a period. If I had to give you a definitive answer however, I haven't spent more than a couple hours total on this and I've been using this close to 2 years now. Did a recap last night and I have a total of 17 bots, some post daily, others I see once a month. I'm also seeing tools being shared here that could make this a lot easier as well such as huginn.

There’s no subscription charges or hosting costs?

None whatsoever. Other than my server which is unrelated (because the same service could run locally) where I have a twitter bot that listens for "save this" from my main account and will unroll a thread and format it nicely for reading later. See https://threadsja.com/ThreadsJa/1214555011289690112 for an example. Used to be personal but I wiped it, got a domain and other people are slowly starting to use it.

So about every service I have connected to it is on a free tier except Ploi (free as well) but I need for actual work and is also too good not to pay for.