What EXACTLY does the summons say?
If the suit is for return of the $450, then you show the judge your itemized bill showing the cost for the work completed. You may need to prove that your costing is reasonable and customary for the work performed in your area. That is all you need to win.
And in that case, mentioning the unsigned contract is immaterial. You don't want to bring extraneous matters in. If he is suing for return of what he paid you only have to prove you earned what he paid.