There are definitely some facts missing, (net lease, gross lease, etc), but in general, I'd say try and get them to sign to a longer lease for a lower amount.
Maybe offer them $1k for 12 mo lease, or $925 for 24 mo, or 850 for 36 mo?
You didnt' mention your costs/mortgage/etc on the property, so I can't really judge how big of a deal the $1,800 is to you?
For reference, I have a condo (in my home town) that I rent to some friends for $1,200/mo, as I had to move out quickly and they were willing to go in immediately. I trust them, generally, and know they wouldn't intentionally do anything to cause harm to my property. I think it could be worth $1.3-1.4k if I listed it, but it's just not worth the hassle right now (it's all equity, so I don't have a mortgage to worry about).
In any case, I think a longer term lease would make the lower rent much more attractive.