No idea on the line replacement cost (at a shop). I've done it (to the ForkenSwift) for about 35 bucks, if memory serves. That was the cost of parts, and I borrowed a flaring tool to make the ends to join the new lines to where I cut the old.
I drove my 2000 Insight for 2 years with no problems aside from normal expected maintenance, and the (known) worn out pack. It was the most entertaining/engaging car I've ever owned -- truly the fuel economy nerd's Ferrari.
If you don't have any sentimental attachment to the VX, and
if the Insight checks out OK, I highly recommend the experience. If you geek out over astronomical MPG numbers and the idea of learning how to operate & mod a unique drivetrain for max. efficiency makes you tingle, it can't be beat.