Mostly 1/12 collectors. If we compare between the 1/6 and 1/12 collectors, this Batwing will appeal more to the 1/6 collectors because they have the budget and requirement for detail, which is why earlier you said why Jazzinc didn't just do a poll with the 1/12 community instead asking his closed group which would sell better, wasn't really the right answer because he's not asking his group which would sell better, he's asking his existing customer base which they'd buy between two choices and only vote if you'll actually going to purchase. He's not going to go to Mafex group and ask whether you'll buy option A at $500 or option B at $500.
One issue is trying to meet the needed numbers with a lower price which is significantly higher than the minimum needed for 1/6 hence, the kickstarter. What are the chances of a mostly 1/6 collector that bought the 1/6 batwing double dipping for a 1/12 version? The point of asking a 1/12 community is to draw in more people from the start. You're fine with this being $500 but guess what, Joost didn't see that with his 1/12 BvS batmobile. The video says it took him 5 years to sell 250 units only (he said 2 and a half hundred). You mentioned HT's the Bat as well which is still in-stock in HK. And HT has far more reach than Jazzinc. So much for catering a 1/12 vehicle to the 1/6 crowd with more budget.
Getting a good number of 1/12 crowd's support along with the right price are more essential than just expecting the small pool of 1/6 collectors to pony up the money. I referenced Tomy's 1/10 DeLorean campaign that reached 3 times its goal in one day. The $30 Neca crowd showed up for that $300 toy. So yeah, I think a lot of 1/12 collectors with less budget than 1/6 collectors will show up for this at $300. $500 highly unlikely but maybe the 1/6 crowd can buy doubles to meet the numbers if you're still willing to pay $500.