a (good/great) deal

"Getting a good deal on something" means buying something for a really low price. For example, if you're looking to buy a new car, you can say:

I haven't bought one yet because I want to wait around and get a really good deal on it.

You don't always have to use "get" and "on (something). You can just talk about "a good deal":

Five for ten dollars? That's a great deal!

It seemed like (something)

Use this expression when you're explaining the choices that you made in the past. "It seemed like..." tells what you thought at that point:

It seemed like a good idea at the time.

It seemed like the car in front of me was going to stop, so I slammed on my brakes.

I didn't ask Joe about the money. It seemed like he was angry about something, so I didn't bring it up.

a no-brainer

A "no-brainer" is a decision that's really easy to make because it's very obvious what the best choice is. For example, if someone offers you a job where you can earn twice as much as you do now, taking the job is "a no-brainer":

When Chuck made the offer, it was a no-brainer. I immediately accepted.

In the example at top, the husband thought that buying the tickets was a no-brainer because of the low cost. But his wife disagreed.

You can remember "no-brainer" by imagining a decision that's so easy to make, even a person without a brain can make the right choice.

(a decision) is a no-brainer

A "no-brainer" is a decision that's very easy to make. You are able to decide immediately without thinking about it.

For example, if someone offers you a job at twice your current salary, accepting the job might be "a no-brainer". You can talk about it like this:

It was a no-brainer. I said yes immediately.

You can remember "no-brainer" by imagining a decision that's so easy to make, even a person without a brain can make the right choice.