Edit: clockwork beat me to the punch: From what I understand, the Gold Lineup of Reeflo pumps come with a 5 year warranty whereas the standard Reeflo line of pumps has a 3 year warranty.
I would personally pay the extra $100 to buy a brand new one and you are covered for 3 to 5 years depending on what model you end up with. I would not pay $300 for a 4 year old Reeflo Barracuda pump. I would say that if the seal has never been replaced, it's probably overdue for a new one...that's 50 bucks right there...bringing you really close to what you would pay for a new one. If you are looking for a deal, try reaching out to Reeflo to see if they are offering any refurbished pumps for sale.
If you are open to using a submersible pump(s), I would consider running Laguna Max-Flo pumps. Not sure how tall this setup is, but if you have 5' of head height, you can run 2 Laguna Max-Flo 2900s that would give you 4,800 GPH on less than 260 watts. They are also super quiet. After running mine, I don't think I'll ever go back to using external direct drive centrifugal pumps. With the Lagunas you don't have to worry about leaking seals or noisy fans...I heart mine- lol.