Geez.... less than 20k original sounds awful nice... but, with the surface rust issues, I speculate its been stored outside for sometime? Was it stored on a concrete pad, or dirt?

Rust can take over in a big way if it wasn't stored properly, and I would guess the undercarriage definitely needs to be thoroughly looked at.

Has it been run regularly? Interior in good shape still?

I would wager to guess that had it been properly stored... that is, the original paint still in good shape, and zero rust, and occasional drives to keep things working, an manual transmission ES with that sorta mileage would be worth 10-15k...maybe more. If only the paint needs done, and everything else is fine... maybe 5-8k.

Other condition issues bring it down even more of course, and if its been stored in a humid area on dirt, the whole undercarraige could be rusted beyond repair...or at least could get very expensive to fix....

It seems good looking, good running, mostly rust free ESs go for the 3-8k range. Them super low miles (if thats accurate) definitely help, but only if its been well preserved.

Them is my thoughts anyhow....
-Matt