If I were you I would shell out the money for the overqualified person now. In a small company the risk of investing time and money in somebody who seems good enough to save a few bucks now could be devastating when you find out the person is seriously underqualified or unfit later, and then you have to deal with the sometimes enormous cost of getting rid of that person. Further if the person does work out and they happen to be junior or mid-level experience, they are more likely to jump ship every year or two than a senior person.
I wouldn't do good enough unless it was a contract to hire, because if the person doesn't work out then they have an expiration date.
The overqualified senior person is the way to go if you are looking to invest long term money and time into an employee. As long as you treat them right, pay them well, and make sure they don't get bored they are likely to stay loyal to you for years to come.