Frequently Apple offers refurb 11 inch MBA on the website for $750. If you can budget for that it may be an option. That item is not offered today but I see I see it almost all the time.
Some private sellers of used Macs are also a source of good used Macs. One I have dealt with over many years and can speak well of is Wegener Media.
The actual machine is presented in multiple pictures. Upgrades and an extended warranty are offered.