Hi David and welcome to the FISD
It is a good idea to use the waiting time for a blaster build and without your last sentence, I would have recommended to contact Derrek (DDay) to get on the waiting list for his new kits...
You seem to look for the DoopyDoo's kits, so yes you are correct - for one their pipe builds you will need some additional parts which will change the price in the end.
The full resin kits have everything included what you'll need (except the scope rail) but sell out very fast. If you really want to go for a DoopDoo's you can leave your email address on their homepage to be informed, if new kits are available.