I know people who build ardupilot based wing systems that have 2 meter wingspans, and flight endurance times in the 1:45 to 2:30 range, all up cost under $4000 per craft. Using fairly normal NCR18650GA batteries and pixhawk cube black flight controllers.

https://www.google.com/search?q=mfd+believer+1960&oq=mfd+bel...