I just passed on purchasing a lot in August. So, quite recently.
I think the people you are talking to are hungry for work, like you said – but also grossly underestimating the job.
I would recommend you do a spreadsheet at 150, 200, 250, and 300 a sq ft. If 150 is a breeze, 200 is ok, 250 is a little tight, and 300 is very tight, then you’re probably ok. I would still talk to some GC’s familiar with Santaluz, though. Santaluz is a whole beast with a special approval process.
But, if 150 is ok, 200 is pretty tight, 250/300 impossible… I would be very hesitant. I have an uncle that builds spec homes for a living. He always budgets 200 – but sometimes it’s 100-150, and other times 250-300 – with the same architect and GC he always uses. There’s just alot of unknowns.