Both polymer and aluminum 80% lowers are more expensive than completed lowers. The vendors know why people want them and they oblige, but charge accordingly. Most vendors include the jig with the polymer lower so that expense is part and parcel to the item. If you want to build one for the novelty and the occasional shooting, probably will last for many years. If you are thinking about every week hundreds of rounds, not gonna last for years.
it was $99 with jig, bits, and shipping all included, figured what the hell.
Going 80% because I just moved back to texas after 2 years away and still dont have Texas License due to covid so FFL is not an option at the moment otherwise I would just order a 100% completed one. Plus I wanted the experience of milling one and figured polymer would be more forgiving to learn on than aluminum.
The gun will be a 300 blackout pistol and will not be used often, going to mainly keep it on the mule at the ranch for when we happen to run up on hogs. Other than that it may get shot every so often.
If you are capable of doing a polymer lower, an 80% aluminum wouldn't be really that much more difficult to machine than the polymer. Pretty much the same bits can be used in either. Aluminum isn't hard to work with.