Very sorry to hear about your loss. I am a fellow Minnesotan as well. If I didn't have so many tanks I would offer to take it off your hands. My best advice to you, check craigslist and see how much similar tanks and equipment are selling for. Being that it's fairly new I would guess 60% - 66% of retail cost is fair. Usually you are lucky to get 50% back.
As autumnsky stated, tanks in that size are pretty reasonable. So it really depends on the equipment he had as well. Lights, hood, filter, any pressurized co2
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