If your buying only what your willing pay, if selling only what someone is willing to pay. Not wanting come across a smartalec but I had a 120gl setup with pretty much everything needed to start a reef for sale & ended up having to drop the price 4 times before it got sold & I started at $1200 which I thought was a great deal.
Bubble wrap the heck out of it & if you can make a shipping container out 2x4 & 2x6 that a forklift or hand operated lift can get under it when you get to where your going & it probably wouldn't be a bad idea to reseal it. That way you know it will be good for another 10yrs or longer.
Marineland 250 .... sounds like a deep dimension tank? 10 years old .... $100 maybe $200. I sold a 4 year old ML265 for $200. Tanks, particularly big ones, don’t hold their value.