personally I think it causes the least amount of bad will if you leave the existing plans at $10*X/year for the people that are grandfathered into those contrac

personally I think it causes the least amount of bad will if you leave the existing plans at $10*X/year for the people that are grandfathered into those contracts. If you increase the price only on new signups you will keep your happy customers... this goes well with an email that says something like "we are raising the yearly fee on the SAAS however the good news is that you're grandfathered into your current pricing for as long as you maintain your subscription"