We did an owner build on our pool, but we paid a friend of mine who is a PB to run the project for us as a consultant. So we paid all the subs directly, at my PB's cost, and then paid him 10% of the total for his fee.
Judging from what we paid the subcontractors, and comparing to quotes we got from 3 other builders, there is about a 20 to 25% markup (so we basically saved 10-15% after paying my friend).
Everything worked out really great, but I could not have done it without my PB friend as I have never owned a pool and never managed a construction project. If I had to do it again, knowing what I know now, and what I have learned on this site, I would be totally comfortable doing it all myself.
We did a similar arrangement with our builder as scdaren. In general (for our market), a builder will put about 25% - 30% margin on their direct costs to cover their overhead, risk, warranty costs, insurance, profit margin, etc.
One thing I will add. In some markets, the trade base is somewhat closed off to the public. They don’t want to compete with builders at the risk of competing with and alienating their primary clientele (General Contractors).
So if trades are willing to deal (& hassle) with individual customers, they typically price in the risks that come along with a virgin, one-time business relationship like that.
So while you might cut out the middle man (so-to-speak), your savings are likely not the full margin - and can even be worse than through the GC.
I worked in general contracting for 13 years before this pool build and did some pricing for myself before I signed a contract with the local builder. While the back of the truck type businesses were less expensive, the well known contractors with established reputations in town (plaster, gunite, excavation) either wouldn’t quote a home owner or would quote things sky high. So at the end of the day, it made sense for us to go through a GC. (Note: Other subs like rebar, tile/coping, electrician, decking were much more open to working with individuals, but the aforementioned big trades were harder to get good pricing on.)
It’s also worth noting that BYOP and % cut arrangements put a lot of the builder risk on your pocketbook. So when things go wrong, if the contractor isn’t to blame or won’t accept the blame, you are stuck paying for the mishaps.
Good luck with your decision and build!
Edit: I have heard that AZ is a much more open market to owner builds than East Texas - so your savings may be more attainable and tangible than here in the Houston area
