DIY would be great if more people had access to a good test facility with better than average mics, all needed software, the skills to use everything and the knowledge to interpret everything correctly. Then, there's the budget to experiment with different drivers, crossovers, cabinets, etc.
Skill & knowledge cut the design to test sequence to a more manageable amount of time, but there's also the listening test phase- has the room been completed?
Look at the speaker company- if they have a lot of employees, that's one of the reasons their speakers are expensive. If they only have a few, it's possible that the price will be lower if they really care about the end product and try to avoid being known for the high price but some want to be known for the high price, regardless of whether they actually sound better or will work with a wider range of equipment.
To Wilson- there's no prize for making speakers that can't be driven by a wide range of amplifiers. That's very similar to trying to win a contest for tightening an oil filter so most people can't remove it.
