I would approach the homeowner either through a hand written note that expresses your interest in their home. The idea is to appeal to their emotional core, after all they may not be in financial distress but emotionally they may want the home to go to someone who loves the areas as much as they did when they purchased it.
It sounds to me like you need to discuss your plans with a sharp Realtor. You can do what you ask.
A Realtor can write an purchase offer, however, I would caution that just because one CAN write an offer, getting it accepted is another issue. The great thing about working with a Realtor is that they will know the local market and the history of that property.
It would have been that the property was actually listed for sale and it failed to sell (expired listing), it could be that it is in fact FOR SALE but there is no sign and it is not in any system other than the MLS.
You know that saying, you only have one chance to make a first impression, so having a professional to represent you in a way that will help you determine if there is truly a way to accomplish your goal.
If you need a referral of a top Realtor in Flint please let me know, I would be honored to provide you with a reference.