Is there a market for dj 45s in excellent condition?

It isn’t the same answer for all of them. It depends on the artist(s), label, and/or song. It is something which fluctuates every day.
To get an accurate answer you have to research.
Some would do better in auction, others would do best from a store.
If you are too impatient to research, and you want an answer right away, then no, they are not worth a cent.

A search will give you the Information you need. Type 45’s for sale.