Have bought 4 used Titanium frames and built them up and like them all, my view is keep a look out on
Ebay/facebook market place etc and if you find a good frame at the right price buy it and transfer the parts.
You could sell your frame to help of set the cost along with any parts that dont fit, dont be in a hurry and consider a stainless steel frameset.
again only my view but life is short so perhaps set a time limit on your search never know your luck perhaps a titanium or stainless bike might turn up this would save you the work of changing parts over and you would not be without the bike, the fun with changing bits over from one frame to another is it can all go great and every thing fits and can be done in a few hours or the opposite can be true and nothing seems to go right and it can take weeks as you have to look for bits and wait on delivery etc.
Worse case for buying a used frame of any material is you find a crack or when you fit the bottom bracket you feel a drag and just know its not a good frame.