From my understanding the industry is quite saturated, and oversellers who give unlimited everything for like $2/mo are killing the ones who don't falsely advertise and give reasonable amounts at a higher price.
I want to eventually get into web hosting and have been working on and off on my control panel (mostly off, due to other projects, but plan to get back to it). I don't plan to make it huge, I just want to make a few hundred bucks a month or so, maybe even hit a few thousand at some point, but that's just a long term goal. I already have a rented server so I'd probably start with that, once I'm making enough money to cover the cost of another server, then I'd get another as my rented server is actually for my hosted game.
I figure if I build a mid range supermicro server with say, 8GB of ram and 5TB of space, I could maybe put 50 or so clients on it depending on bandwidth costs, but that's just a rough estimate. Things to research further.
Well, I went into hosting business with that idea more than 2 years ago and I got a dedicated server. There are few things you should know first:
1. Things will NEVER be as planned
2. Expenses will always be higher than you've calculated
3. You will have to have solid knowledge about the administration.
4. Be prepared to loose money in the first 3-4 months (unless you have a 30 clients ready to move to your hosting immediately ).
5. To make few thousand bucks a month - you will have to go HUGE
For the start - you should get few clients and I recommend you to buy some reseller plans until you build client database. When you get 30 clients (that will pay you $6-7/mo) and when you get $200/mo you can start thinking to buy dedicated host.