Decide what car and spec you want then spend a day calling to several main dealers of your chosen model and go with the best offer, in my experience there has always been a huge variance.
As you say a lot of these scrappage deals have conditions and they vary greatly between different manufacturers but they all want to sell you a car and will offer you a deal with or without scrappage / finance / trade in.
My old car is not too well but I hope to get into 2016 and buy a new Toyota without finance then. If I don’t make it I will have to buy this year so have been keeping an eye on Toyota prices.
Toyotas current €3K scrappage offer is not dependant on taking finance and appears good but when they announced it in June they upped the price on most models by €1K or more, so list price today, from which you get the scrappage is probably artificially inflated.
It still might be a good deal, just not as good as they would make out.