Doug, don't listen to all these guys who think that all is a ripoff.
It's just up to you!
Sinsot is not a farang cheat thing, all Thais that I know payed sinsot.
Speak with your wife and explain how much money you got, you as a couple. All the money you spend on sinsot will come from this amount. It's not your money, it's the money of the new family you are going to build.
Speak with your wife and explain your expenses and your income, find a way to support your new in-laws with a monthly appropriate amount that you can afford.
Be happy, enjoy your new family, don't listen to me and anybody. Do your thing.
Good luck and have a happy life with your Thai wife.