I can't name them off the top of my head but there are dozen's of SaaS companies who have done this. Some even went from FREE to only paid.

I would suggest the following
- Don't raise prices on existing customers unless you absolutely need to, to stay alive
- Test it first without build anything by updating your pricing page and see if there's a huge drop in conversions.
- Try starting with 50% increase first.

Just so you know, it's not about the price, it's about the value your product delivers. My rule is: How much $ do we save a company, then divide that by 3, that should be a good ballpark for pricing.

Hope that helps.