(something) is on the market

You say that something "is on the market" when it's being sold publicly.

Examples of things that can be "on the market" include:

• houses that are being sold
• products that a company is selling
• a company that is ready to be bought by another company can be said to be "on the market"

It's a bit of a joke, but you can also say that a person is "on the market" if they've just become single and are ready to date people:

Watch out, ladies! I'm back on the market.

When you first start to sell an item, you "put it on the market".

a find

When you've found something that's really exciting, very rare and valuable, or a really good deal, you can call it "a find":

A: Can you believe that they discovered a new anti-cancer drug just by accident?

B: Yeah, that was quite a find!

Helen, your new boyfriend is so cute! What a find!

"A find" is something to be excited about.

(something) won't stay on the market for long

You say that something "won't stay on the market for long" if you think that it will be sold quickly. For example, a nice house that's priced cheaply:

If you find a house that you really like, it's best to act quickly because it probably won't stay on the market for long.