I think anyone would be hard pressed to find an original 65-70 Shelby project under $30k. Lots of folks cannot afford the average Shelby entry point, which is probably close to or at 6 figures these days. While this does afford someone a low initial cost, these major projects almost always end up costing more in the long run. But, to some folks, the journey to the finished car is worth more than clicking an easy button.
The dash and Shelby tags being missing does impact the car some, but it's not a kiss of death. My '68 has a repro Shelby tag. The previous owner had the car since the early 70's and used to keep it parked outside. He removed the Shelby tag in fear of someone stealing it. Unfortunately, through a couple family moves, the tag was lost. It is what it is, but there are cases where a repro tag doesn't mean someone is trying to cover up questionable/bad history.