How can I find affordable dental insurance in Delaware?

My guess is the same as you would anywhere. Start with your employer, see what (if anything) they offer. Ask friends. Make calls.

Try Ameriplan. It's not insurance but a discount medical plan.
www.ameriplan.com

If it has already been determined that the braces are needed you will be charged pre-existing condition rates. That means you will eventually end up spending as much as the braces cost. You are better off trying to negotiate with a dentist (pay cash, ask for a long term payment plan), check out what a dental school would charge (NYU has an excellent public program), or check prices in Mexico and Canada. I know someone who was very happy with the braces their son had done in Mexico, and even with having to pay air fare, it was far cheaper than having it done in the US. They used a local dentist to do check-ups and when it was time to remove the work they went back to Mexico.

In the meantime, I suggest you work along with small business people like myself to demand the US government fix this mess. Here are places to start:

http://www.aarp.org/issues/dividedwefail/get_involved/

http://www.pnhp.org/