It depends on your market. Some markets would consider source-availability an advantage; most wouldn't. Are your competitors making source available? If you have no competitors (which I really doubt) find a comparable product selling into the same market.
A related issue is license enforcement. Lots of shrinkwrap (meaning, not hosted by the copyright holder) software incorporates licensing code to discourage installing the software on multiple servers without paying for it. Again, this decision must be made with sensitivity to your specific market. If your competitors don't protect their code, you shouldn't either.
Obviously, all licensing code relies on security through obscurity. If you offer customers the source, and choose to enforce licensing, you have an interesting technical challenge on your hands.
The only positive I can see to source-availability is a hedge against your company going out of business. A technically proficient customer such as an ISP can then continue to maintain their instance.
A big negative, both for you and for corporate customers, is that customer employees may modify the code, leaving it in support limbo.
I recommend laser-like focus on the market you plan to serve. Incidentally, such a focus may cause you to reconsider your $30 price point.