A few years ago I was selling HID conversions from a company down in Industry, CA. using the product name Eagle Eye.
The company was known as a budget (as in cheap) Chinese import company, but hired an ex-Sylvania engineer and was doing conversions in-house that were, although not strictly legal, at least adhering to DOT standards so as to not blind oncoming traffic with a visible arc or bad focusing. Adding shields as needed and positioning the bulbs at the proper depth for whatever lamp they were fitted into.
You could even get the 50 watt upgrades for off-road action if the 35 watters weren't bright enough for you.
Not sure if they ever came out with a shallow conversion version that would easily fit the Bronco buckets, without modification, but they might have. Would be worth looking into anyway. Assuming they're still in business.
Lots of competition in the last ten years or so, but they were one of the first to start offering less expensive alternatives. Even then though, they were still coming in at the $500 mark for a pair.
Jenn Fang Co, was the company name, even though the lights were sold under the Eagle Eye name. Might have something worth looking into.
Paul