Our business model (at least for the first 5-6 years) is awfully similar to a farm. We are investing nearly all revenue into producing our crop (the software) by making 100's of small and large improvements per year. Without a subscription (selling each year's crop), the pace of improvements would get cut dramatically. If we get a good feature request today (a smaller one), we can seamlessly push that live to all user accounts in under an hour and we've done that many times.
I definitely understand where you're coming from though. Your goal is to buy a product for as low of a price as possible and I don't blame you for that.
We work with numerous farms under 1,000 acres. If you'd like to talk, shoot me an email. -Nick