I echo most of the comments here.
I guess there are two main types of builders: those who just build a kit as is, and those who treat the kits as a base and upgrade them to what they want. If the upgraders are spending $200 for the kit they may then spend another $200-400 on upgrading to the hardware, pickups and electronics they want. So, the kit's neck and body are just the base and the cheapest part of the build.
If the premium kits offer a major step up in wood and quality (and QC) for the bodies and necks and have equivalent hardware/parts, then prices of $600-800+ become potentially viable. You could get the guitar/bass you want from the kit as is, rather than modifying, fixing, adjusting and upgrading a cheaper kit to get something close to what you want. That said, $800 outright is a lot harder to justify/obfuscate than a $200 kit with gradual upgrades.
Looking forward to seeing the samples.