@ stm, I don't disagree with you, what I'm saying is that advantage is relative to what it is valued at.
The seller making 30 bucks can then buy 30/70 of his own product if he so wishes. He has to sell 3 units to make himself enough + margin to afford one of his own gizmos. The buyer saves 250 in his own terms (else why would he buy, you are correct there). But what he has bought he cannot sell for 350, he would maximum sell it for 100, likely less because he doesn't have the reputation the original seller has, the seller retains much of that part of his wealth. Besides, the buyer on-selling would not make money (different to retailer margin, they make money by providing services to the manufacturer - increasing merchantability of their goods with retail skills). However the seller makes those 30 bucks each time.
In the case of your example of an accountant selling his skills to the employer, the employer is making more than what they pay the accountant or it wouldn't be worth it. Alternatively, the accountant enables better extraction of value for the company from other assets, taking a fee for that through better wages or bonus or commission. At that point, you can differentiate between an accountant who is doing what he's told and makes minimum and the one that is consulting to the company and making serious money. You'd have to agree that the latter is wealthier. This is what I mean by relative advantage.
Both accountants are accruing wealth. The company also accrues wealth. But the company accrues a different % of advantage relative to either employee. The employees in turn accrue wealth at different rates. Skill and knowledge of many types is central to it. In real terms, most likely, the wealthier accountant is helping the company leverage extra efficiency from the employment of the other accountant, so he is indirectly taking money off the other guy - i.e., your manager is making money off you, getting wealthier. If he didn't, you might be able to do say 50% as well for the company as he is making you do but you'd also be able to charge more while the company makes less money. Hence why companies tend to merge business to bring partnered skills under the one umbrella to leverage off each other.
Essentially I maintain that wealth is relative to another. I might be wealthy relative to a couple of people and poor compared to 97. That makes me the 98th wealthiest. To gain advantage I will have to use some skills to make more than others, either increase my advantage on the 2 poorer than me (mostly organic growth) or try to gain additional advantage (acquisition/contracting to bigger and competition etc) on those richer than me. In the process, might be that everybody gets a little richer with time but that only goes so far as the basic resource you are exploiting. If we run out of manpower or energy or natural resources then to get wealthier we are basically taking each other's share to keep climbing the wealth ladder. Make sme think that capitalists have the best understanding of a finite market, growth equaling shrinkage elsewhere.
PS: also brings to mind 'what so generosity'. I'd say generosity has types. There is cooperative generosity where you don't press your competitive advantage to generate wealth for yourself. I.e., selling the gizmo for 70. Then there is charity, which is giving a discount, on your labour charge for example. Then there is stupidity, where you discount deep enough to be below actual acquisition cost. That is a reduction in value for your goods. Selling for 80 instead of 100 is a competitive discount, not generosity.
