My advice…get your home inspected, even if you are not planning on selling. Think of it as a wellness exam. You will get a good understanding of how your home works and what maintenance it needs going forward. Think of it as a checkup for the health of your home. EVERY home has issues of which the owner is not even aware. A complete “checkup” 
including septic ($400) will run you about $1200. The other alternative is, if you think you might have a specific issue (like I did with my electrical system)is to get it evaluated by a tradesperson. You should PLAN on spending $3000+ each and every year on your home. This year it is repointing the chimneys for my home AND doing some tree work. Ignoring and postponing maintenance projects will only allow the home to deteriorate further and cost you more in the long run.
Since I do NOT like surprises, I always advise my clients to at least get a thorough septic inspection. I get pushback from Seller who say, but I have it cleaned every 3 years. It is NOT the same thing. The items that come up the most during building inspections are septic issues, electrical issues, decks, water quality and mold. In the past year, I had an electrician do a complete evaluation of my own electrical system. Every outlet had reverse polarity, mice had had a field day with some of my wiring and my house wasn’t even grounded. Many of my clients have found mold in their attics. This is not as scary as it sound but wouldn’t you like to know if your family is being exposed? Well contamination is an issue about 50% of the time. You should be testing your wells annually, but who does??
Pre Inspections is a question that agent have been debating for several years. I get asked this question by Home Owners occasionally myself. Most Sellers have a mental budget of how much they will spend getting the home ready for market. It is generally between $5000-$10,000. Just as you wouldn’t take your car to be sold without a good detailing, you shouldn’t think about marketing a home that hasn’t been well prepared. The Realtor will advise you on paint choices, getting the windows washed and things like that. Your REALTOR can not advise you on hidden and structural defects. These WILL come up in an inspection. While your Realtor will help you to “DETAIL” your home, the inspector is the “MECHANIC” who will make sure it is in top structural/mechanical shape.
For recommendation for who should inspect your home and your septic call me at 203 994-3666.