you took the chance to keep your life a bit simpler than it could be;nothing wrong with that. we all got too much stuff complicating things more than need be. good choice on passingand ad mirable self control.
Lenses engraved "8 1/2 x 6 1/2" will cover that format, which is larger than 5x7.
Are you a dolt? You might be, in which case welcome to the club. But be passing on what might have been a good buy is not particularly doltish behavior. If you know your Uncle Remus, remember the tarbaby.
Are you a dolt? You might not be, you could be averse to risk or, like me, completely unaware of such lenses' market value. I second Ralph's comment.
If you really needed that lens you might have passed up a good opportunity.
But so what? It doesn't really matter. There will always be more lenses.
My own philosophy is that I can only use one at a time, and probably only really need one lens. Maybe two. More than that is simply indulgence. Never lose sight of your goal and what it is you want to achieve with your pictures. If you always keep that in mind, it's amazing how much better decision making becomes.
Im only unsure of it because the word Dallmeyer screams ridiculously expensive and I thought about flipping it for some decent profit to put toward a Schneider 300 or maybe a Super-Angulon
No no no, by NOT buying it you have already made a profit of $125; you need now only not buy a few more lenses and you will have more than enough for your Schneider or S-A