If it's from a store with a warranty, that's a good thing. The chassis of the Mamiya 7 is made of plastic, so do
- Check it out for dings/cracks/damage.
- Make sure the iso/shutter/mode dial is in order.
- Check that the 120/220 back plate is in order and swivels as expected
- Light meter (I find mine quite accurate, meter off darker areas and light)
- Check that the inside is clean and free of dust.
- Check that the curtain moves into place and releases nicely.
- If you are getting the 43mm lens, make sure you are getting the wide angle view finder
Mine is a 7ii (difference is multi-exposure and the lens change curtain mechanism).
As for the price, I think it's good. I paid $2300 for a 7ii with 80mm & 65mm lens. All in excellent condition. The 43mm lens and viewfinder cost me $1000 alone. So, if yours is in good condition, I'd say that sounds like a sweet deal.
Enjoy, of all my cameras, I love my 7 the most.