The C2 Armory Trader pays the highest prices for loot! The C2 Armory Trader also has the lowest prices found( up to 60% off from other traders) for all things in the Armory. As a noteworthy point, anything related to M82A1 requires a fame score of 720 to purchase.
The M82A1 rifle,parts and ammo can be bought at other traders. It only requires a fame score of 350 to buy this equipment.The only downside is it's cost and at up $50,000 more per rifle and ammo isn't cheap either. So buy it now at higher price and lower fame score OR buy it later at cheaper price, because you have a higher fame score.
The B4 Medical and General Goods Traders pay the best by around 50% more then other traders. They also sell around 40% less on their products.
The A0 Mechanic trader pays the most for mechanic parts and also sells everything in stock cheaper than any other trader. You'd be stupid to buy a car from any other dealer!
The Z3 Boating Trader is the place to go to sell your fish and buy all things fishing related at the cheapest price!