Ask HN: Why technology is not hot about solving real life problems?
Custom engineering design and construction is very expensive because they cannot amortize the costs over many units. If it was like tomatoes, that is being produced by the thousands then you would be able to get a very specific price.  But one-off are very hard to cost, especially in the absence of detailed design and specification.<p>You might be better off looking at what the established farm machinery companies are doing, for example 
John Deere has an autonomous tractor.  There are also many companies who retrofit GPS and other automation to existing farm machinery. I found thousands of different automated farm machines with a quick Google search, so I don&#x27;t know where you have been looking.<p>Another option is to contact the engineering faculty of a nearby university, they might be interested in solving a real world problem if you can produce a preliminary requirements specification.