Have you dug around near corners of PL looking for surveyors pins?

Borrow a metal detector to find the pins.

Those prices seem excessive; I had my property surveyed two years ago and it cost about $650. I know that CA and NJ are in different universes, but that much difference?

what all is included in that survey cost? Unless it's a huge lot, that seems astronomical even for CA. They're not including doing a full topo or anything, are they?

You may want to call another survey company. Some companies provide service to just come out and put flags on property lines. When we get whole landscape surveys with contours and elevations drawn up in cad then we are charged closer to those fees up here in LA. Maybe they over sold on the services and you don't actually need the whole survey plan? But even if you look into the cost of a fence a fence will cost way more than a survey so getting it in the right spot is important.

Maybe this will help: costs involved with a property survey.