I had a similar gouge in the glass on my 125g and it has been fine for almost 4 years i think it is....I did however fill the crack with windshield repair 2 part epoxy. I let it cure so that it pretty much filled in the hole and made it less pointy.
Not sure I would say sure, go ahead and get it, no worries it will be fine, I got my entire 125g setup for $100 so it was worth it. But you can most likely find a comparable tank without the crack.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.