It is dangerous to try and correlate the price of drivers in a speaker to its quality or value. It starts with two incorrect assumptions 1) that driver quality is directly proportional to its price, and 2) that driver quality is the primary factor in the quality of a speaker.
A speaker, like most things, is the sum of its components, quality of design, and implementation. Amazing drivers in a poor enclosure with a poor crossover make for a poor speaker. Decent drivers with a well designed and executed crossover and enclosure make for a good speaker. At the end of the day the only way to evaluate the value of a speaker it to look at the end result and see how it measures up to its competitors.
A perfect example is the Philharmonic BMR. It measures well, has excellent subjective reviews and is considered an amazing value at $1,700. It uses expensive RAAL tweeters and depending on the generation Scanspeak or SB Acoustics woofers. However, the speaker was designed around the BMR midrange, which was actually designed as a full range small driver for inexpensive bluetooth and portable speakers. The BMR drivers cost something like $20 a piece. Dennis in designing the BMR didn't care the driver was $20, he cared that it had amazing measurements, great out of band linearity, low distortion, and was the perfect size to bridge the smaller RAAL tweeter and the woofer.
If your sole motivating factor is buying speakers based on the BOM cost, you will be hard pressed to do better than internet direct sellers. Ascend Acoustics, Philharmonic Audio, and Salk all provide a very high BOM to sale price value. I am sure the BOM cost for Revels is far lower, but their execution is flawless, part of what you are paying for is their vast research and experience.