I've recently the post on the question: Subscription Pricing Starting Strategy: start high and lower, or start low and raise?, and I also read the articles and comments for:
1) What are the advantages and disadvantages of pricing a monthly subscription low, and then pricing it high?
2) What would you say is the "sweet spot" that still attracts customers, but doesn't attract the cheap ones. I realize this question is very subjective, and you probably need more background on what this business does... at the moment, the business owner isn't sure yet (all in planning), I'm just curious on any two cents you might have (eg. $99/month typically deters most cheap-folk)... although, I'm not sure this is answerable.
3) I'm a fan of simplicity and I advised that 1 price with 1 plan is a good idea... but maybe a 3 or 5-tiered approach is better. What are your thoughts on 1 plan versus 3 or 5?
Good advice above. Here are some more data points for you to consider:
Initially, it's very hard to tell what the "sweet spot" pricing for the product is since every market is different. If you are selling to individuals, $99/mo is pricy, when selling to big businesses it's very cheap. You do know approximately what your fixed and variable costs and you want to make sure those are comfortably covered.
In our case, we sell a SaaS application for which we bill monthly and our target is a very small/niche market with a few thousand potential clients.
When initially pricing our product I started low with the intent to raise prices for future customers. My reasoning was that since the software is new and has no users we need to have early adopters as soon as possible to get feedback and build a reputation in the industry.
Since the early adaptors were taking a chance with us they were rewarded with lower pricing. Furthermore, we offered customers an opportunity to "sponsor" features (e.g. pay us hourly to implement features specific to their needs). This helped with prioritization and made up for the discounted monthly fee with consulting revenue.
New customers are only aware of the "current" rates which we post on our site. I try to price our product so that we make a profit while making sure cost is not the critical factor when signing on new business. We have increased prices several times (for new customers only) and also added usage-based tiers to attract some of the smaller customers.
There's a science to pricing, and it seems even when you find the right price, you still can't tell if it's the right price and may try to move it from there. For example, you might set your price as $49.99 a month, which is perfect, but then you decide to try $59.99 a month and you lose 40% of your customers.
As was pointed out in other answers, the first thing you need to do is determine what value you provide to your clients. The next thing you should do is determine if the value is obvious (for example, by removing an existing cost) or implicit (for example, increasing their business volume). If it's obvious, you can use it fully to price your product, but if it's implicit, you have to be a little more careful because your customers won't see the value right away.
That being said, even if you can show how your product provides $100 per month in value, and get the client to accept that fact, you shouldn't charge that much. If you take all the money they save by using their product, there's no incentive for them to continue using your product.
My rule of thumb would be to start at about 50% of the demonstrateable benefit, and work your way down until you find a point you're comfortable with. Anything over that, and some of your clients will become resentful of your cut, especially if the cost to you for providing is negligible. While most people accept that you have to earn a living, they don't like being ripped off.
A lot of people don't consider the price of providing support after the sale. Don't underestimate this. You might receive a lot of emails for support where people are asking all kinds of questions even questions whose answers are already in the FAQ just because it's easier for them to ask. You will find yourself spending too much time in the support area taking time away from product development.
So always offer a higher price with support option.