I've seen a fair number of folk trying arbitrage, most had some success with it, most do not stay with it long. I suspect few folk playing this game have the temperament for playing long term retail merchant, especially when there are so many other more intriguing aspects of this game.
I reckon it depends on your viewpoint.
Me? I'd never sell a Traz or CF or Arc or other advanced GB to a newer player. Not without a long hard look at their city and a fair number of probing questions. Mostly i'd be trying to find out if they are anywhere near the point in the game where it would do them any good, both how to use it and if it would do them any good.
Getting a GB the player isn't ready for is somewhere between bad and a nightmare. Watching some sub 50 FP per day player with a Traz and no combat GBs is painful. Watching sub 100 FP players with Arc is hearbreaking.
You'll be doing them more good by teaching them how to get into position to use and level those GBs. Then when they are ready, they'll come to you for the Goods sale and maybe more?
All the market will bear is a fine short term strategy. I'm not all about profit, I'm about helping folk. It's much better for long term business, and a hell of a lot of fun to see your customers grow. I spent 2016 in ProgE selling Traz Goods to my Guild for 35 (thirty five) FP Ever since I've been the go to guy for any Guildie needing anything. Last year I spent a lot of time on the road visiting other Guilds and selling stuff. I sold cheap (Traz and CF 150, lower Era GBs cheaper or free, Inno not so cheap at 350), This year I'm getting as many requests as I can handle through word of mouth asnd repeat business . Since I do have a reputation as being helpful I get additional referrals of helping out with 1.8ing folks powering their GBs.
So if all you want is short term profit, go right ahead, sell at full market price to folk who don't need what you are selling. You may find that fun, but I suspect you'll soon get bored with it.