While I don't have any personal experience with using the BPS kit, they look like a quality kit. It all depends what you want in the end. I think the BPS kit may give you a little more polished/store bought look on your cooker vs. putting one together with pipe nipples and bolts, but functionality will be about the same should you choose to build one using hardware store parts-given you build it within the typical UDS guidelines. Like others, I don't really see the issue of "running around gathering parts"- most parts are available at the big box stores(bolts,grates,pipes,paint)...there ain't much else goes into these things.
UDS'-55&16, Akorn, Bar-B-Q Kettle, Drum Grill, miniWSM, cobweb-covered gasser. I'm JD.