Haggling Events Table (which is the only use for Haggler as the skill is described) does seem to be something of a sucker’s bet. So let’s take some time to crunch numbers for perspective:
Assuming the Haggler Test succeeds AND you have a piece of 2D treasure (not coins, which I’m pretty sure also means not “gems” by inferring the “Treasure and Valuables: Spaces to Value” table and footnote on page 92), you can better than break even on a roll of 13+, which is roughly 1/4 of the time (25.9% to 3 sig digits). If you fail the Haggler Test (but have a Treasure => 2D) by just 1 that drops to 6.5%(!), MOF 2 is %3.2, MOF 3 is below 1%, and MOF 4+ you can’t better than break even.
Note that if you don’t have at least one 2D piece of treasure (and sometimes you’ll not even know if you do) even succeeding only gives you <5% chance of coming out ahead.
Given that you need Ob2 for even the most easy place to Haggle, beginning characters are likely to have a base chance of 25% or 50%, for %6 or %13 upside odds. That seems a pretty bad deal on the face of it.
The result of 9 complicates this all somewhat with the potential for snagging an extra expensive item if it has purpose and you’ve got the dice for it.
What about the “break even” range? Most of the time you’ll come out slightly worse (a +1D for a +1Ob Resource Test for Lifestyle). BUT this is only notably worse if you have an expected Lifestyle nearing 1/2 of your Resources stat. Any outcome that gives you a +1D in Treasure is pretty much a wash as it insulates you from the Tax of the +1 Lifestyle, as is the case if you are just popping into town because your friends are hurt (or you are visiting ‘free lodging’ because of friends/family/etc.) and you have Resources of say 4 or 5.
Further Help + checks could really tip the balance here as your teammates can convert checks into test logs for even less downside risk.
Without digging deeper into the numbers here, it seems that Haggling is a somewhat viable option for advanced PCs that come into town already in a good position, but does represent some wild-swing risk and long shot on payout. It is however a sucker bet for PCs that are weak or in trouble.
Now to my feeling on your two suggestions separate:
Allowing addition of up to MOS on the roll, the odds change drastically. Piling on with Help and Traits and maybe a Persona to tap Nature (or potentially even just Fate, for those Demanding Humans!) you’ve got a slam dunk. If they’ve dragged a +4D Treasure into town eek! Too rich I suspect. Trading what is arguably an issue of ‘trick’ false choice for another issue.
Take 7? Well damn, that makes it boring. Plus it effectively kills the chance of a big payout.
I don’t feel that good about Haggler, as constructed it feels somewhat like it is all cruft. But I like your suggestion less.
P.S. I respond here with the assumption this thread will get moved to Hacks.