I think I've found a formula for the options scenario of the OP:
Code:
For an ATM option with r=q=0 (ie. S=K which also means p=0.5 for UP and DOWN) it gives:
leverage_factor discount_(ie._rebate)
1 0%
2 12.5%
3 16.67%
4 18.75%
5 20%
... ... (upto max 25% possible)
So, then the broker can advertise "Buy 5 of our newest option product and get 20% discount!"

(in reality it's of course just 1 of these new options with 5x leverage)
This of course also applies to the option writer side, but of course here the credit the gets is 20% less than with normal options.
But since the payoff for the buyer is the same as with normal options, then this means it is the option writer who bears the additional risk (of the rebate he gave the buyer).
Can this function? Still testing...
I don't think this is practically possible. 2 identical instruments can't be priced differently unless there is a liquidity advantage of one vs. the other. If both are identical, they should be priced the same or very close to eliminate any potential arbitrage.
I remember back in the old days, I believe it was in 2007, CBOT (It was still independent at that time, not part of CME) introduced mini agricultural future contracts (For Corn, Wheat and Soybeans). The standard contract was for 5,000 bushels, the mini-contracts were for 1,000 bushels each. Everything else was exactly the same.
On the day those mini-contracts started trading electronically, there was a large discrepancy in their price vs. the standard contract in the overnight electronic trading, i.e. when the pits were closed. It was a clear arbitrage opportunity and that was due to thin liquidity in those minis in the overnight electronic session.
I remember very well that I spent almost 2 or 3 weeks arbitraging this until it was gone and prices finally aligned with very narrow differences where it became unprofitable when taking transaction costs into consideration.
During those first 3 weeks, it was very normal to see a difference in prices of 5-6 points (That's $250-$300 per 1/5 contracts), i.e. you find ZC (standard) bid at 500 @400 and the XC (mini) offered 20 @395, it was basically free money, you buy 20 @395 and short 4 @400, that during the overnight session, and the next day when the pits open, prices align and you get out booking your profits, and so on.
Moral of the story is that as long as there is something fundamental which justifies a difference in price of identical instruments, it can never happen or is not sustainable.
Offer me this new option with 5x leverage at 20% discount, I will only buy it if I can offset it with by shorting 5 contracts of the 1x leverage, thus squaring my position and booking those 20% in my pocket, risk free essentially.
Change the contract specs and you have a new instrument, in this case, it can be priced differently and based on the changes you do to the contract specs, you have a different pricing formula & a different price (Other things being equal).
Sorry for the long post, but hope it helps.